The Project Gutenberg eBook of Parasites; a Treatise on the Entozoa of Man and Animals, Including Some Account of the Ectozoa, by T. Spencer Cobbold.

Fig. 47.—Adult male Oxyuris vermicularis. Magnified. After Küchenmeister.

From the united labors of Professors Zenker and Heller it is now rendered certain that all the further changes necessary to bring the larvæ to sexual maturity are accomplished within the small intestines of the human bearer; and it is not necessary that a change of hosts should occur at any time during the life of the parasite. Infection ordinarily takes place by the accidental and direct conveyance of the eggs that are lodged in the neighbourhood of the victim’s anus to the mouth. Since the victim may accomplish this during sleep, it is not in all cases fair to charge infected persons with uncleanliness. On the other hand, it too often happens that due care in this respect has not been exercised, and from such persons you may remove the eggs of Oxyurides from the margins of the finger nails. One aristocratic person, who was infested by myriads of these entozoa, confessed to me that in his extreme distress, and consequent rage, he had freely bitten the live worms in halves between his teeth. He had thus exposed himself to a terrible revenge, since multitudes of the ova entering his mouth subsequently found their way into the stomach and intestines. By whatever mode the eggs are conveyed to the mouth their subsequent passage to the stomach ensures their being hatched. In the duodenum and other divisions of the small intestines, as Zenker and Heller have shown, the embryos undergo transformation, casting their skins, and growing with great rapidity. Probably not more than three weeks or a month is necessary to complete their growth. Heller obtained mature worms from an infant only five weeks old. Finally the worms are transferred to the cæcum, which constitutes, so to speak, their headquarters. It is an error to suppose that the lower bowel or rectum forms their especial habitat, nevertheless the most approved manuals, vade mecums, and general treatises have for a long time supported this erroneous view. The error had been pointed out by Stricker in 1861.

The symptoms produced by Oxyurides are occasionally very serious. In the mildest cases they have a tendency to undermine the health. As remarked in my ‘Entozoa,’ the unpleasant sensations chiefly develop themselves in the evening and at night, consisting for the most part of feelings of heat and irritation within and around the margin of the anus. The symptoms may become extremely distressing and almost intolerable, especially when the itching extends to the genito-urinary passages, in consequence of the escape and migration of the parasites about these parts. By-and-by various sympathetic phenomena, such as restlessness, general nervousness, itchings at the nose, involuntary twitchings, grinding of the teeth during sleep, chorea, convulsions, and even epileptiform seizures, may supervene. At the age of puberty special local disorders arise, the nature of which will be readily understood when merely spoken of as the morbid phenomena of sexual irritation. In the female the occurrence of pruritus and leucorrhœa is not uncommon, accompanied or not, as the case may be, with hysteria in various forms. There is usually general asthenia, with more or less emaciation. The anæmia is sometimes remarkable, but in place of anorexia, which is, however, an occasional symptom, one frequently finds a most voracious appetite, especially in young people. Sometimes there are obscure symptoms simulating those of local organic disease.

About the treatment of the disorder I have nothing to say here, further than to urge the benefits of the preventive measure of cleanliness. Like Zenker and Heller, I have obtained the eggs of oxyurides from beneath the finger-nails of young people. In one lad all the nails had been carefully bitten down to their roots, but from beneath a minute projecting portion that was left on the right fourth-finger I procured two eggs. Their demonstration under the microscope convinced both parent and child of the necessity of frequently employing local and general ablutions. Personal cleanliness is essential. In this connection an able biologist has ventured to hazard a statement to the effect that “probably any infected person who adopted the requisite precautions against reinfection from himself or others would get well in a few weeks without treatment by drugs.” Dr Ransom bases his belief on the known facts of the life-history of this entozoon, as recorded more especially by Leuckart. I regret that I cannot fully share Dr Ransom’s views, and still less should I think it right by my silence to seem to endorse his statement to the effect “that every person who is shown to be infested with those very common entozoa, Oxyuris vermicularis and Trichocephalus dispar, is thereby demonstrated to have swallowed minute portions of his own or another person’s fæces.” This is putting the case too strongly. No doubt the eggs of oxyurides swallowed by ourselves must have previously passed through some person’s rectum; as such, either separately or mayhap collectively, in the body of the maternal parasite. That does not, however, justify the statement, that we “have swallowed” part of our own or of some other person’s excrement. The eggs ought not to be regarded as constituent portions of the fæcal matter. Perhaps Dr Ransom will say that the surfaces of these eggs, being in contact with fæcal matter, must carry infinitesimal particles on their surfaces, and it is to such that he refers. As, however, a large proportion of the ova escape with their parents, whilst they are still lodged within the maternal worm, it cannot be held that these intra-uterine ova carry fæcal matter on their shells. Commonly the eggs are swallowed in the separate, free, and dry state. In water they perish quickly. The act of eating with unwashed hands is a fertile source of infection, more especially if the meal be taken either in bed or in the bedroom.

Leptodera (Anguillula) stercoralis, Bavay.—In the summer of 1876 Dr Normand, of the French Marine, discovered this little entozoon in the fæcal discharges of soldiers who had been sent home invalided from Cochin-China. The patients in question were the victims of the so-called Cochin-China diarrhœa or dysentery. This disorder is endemic in character, and it had hitherto been regarded as consequent upon a variety of causes other than parasitic. Dr Normand’s discovery, as such, therefore takes equal rank with the analogous revelations made by Bilharz, Harley, Leuckart, Zenker, Weber, Lewis, and Bancroft, in respect of the particular helminthiases in man with which their names are severally associated (Bilharzia disease, Endemic hæmaturia, Cestode tuberculosis, Olulaniasis, Inter-tropical anæmia, Trichinosis, Lymphoid affections, Helminthoma, and so forth), and also, if I may be permitted to say so, with my own determinations in respect of a variety of endemics affecting animals (cestode and nematode epizoöty in the horse, the so-called grouse-disease, the pigeon-endemic due to lumbricoids, &c.).

The Leptodera stercoralis is a minute, smooth-bodied, simple, rhabditiform nematode, measuring when full grown 1/25″ in length, with an average breadth of 1/625 of an inch. The embryos at the time of their extrusion measure only 1/250″ in length, but by the time at which a rudimentary vesicle representing the uterus begins to form, the females have already attained a length of about 1/83″. The males and females are of nearly equal size. The transition from the embryonal state to the higher larval conditions is accompanied by a change of skin, after which the digestive and reproductive organs are gradually but rapidly formed and completed. These changes have been minutely traced and recorded by Professor Bavay, who also compares the entozoon with the genera Rhabditis and Leptodera, in either of which genera the worm might be placed. I have accordingly adopted the nomenclature suggested by Bavay.

Fig. 48.—Leptodera intestinalis. a, Adult female, and separate figure showing a portion of the body with the ova in sitû. The two outlined figures represent profile and front views of the tail, respectively. b, c, Eggs with imperfectly formed embryos. d, Larva. Highly magnified. After Bavay.

As happens in all the kindred helminthiases that are known to be dependent upon the presence of small worms, large numbers of Anguillules are necessary to produce injurious effects upon the bearer. Thus, the evacuations of the Cochin-China patients were found to contain such multitudes of the worms that their numbers could only be adequately estimated at so many hundreds of thousands passed in twenty-four hours. Of course they varied in quantity, not only in different patients, but in the same bearer, from day to day. They are to be found in every stage of growth and development, from that of the intra-ovular embryo and free embryonic state up to sexual maturity. They occupy all parts of the intestinal canal, from the stomach downwards, being also found in the pancreatic and biliary ducts, and likewise within the gall-bladder. According to Bavay, five days suffice under favorable circumstances for the complete maturation of the worm. This readily accounts for their occasional extreme abundance.

I am indebted to the courtesy of Dr le Roy de Méricourt for the original memoirs from which these brief abstracts are taken.

Leptodera intestinalis, Bavay.—This is a larger species, now and then found associated with the above, and, according to Bavay, “in infinitely less abundance.” This species was also discovered by Dr Normand, and has been carefully described by Bavay. Possibly the worm may afford us another curious instance of dimorphism. Be that as it may, it must be provisionally regarded as a distinct form. As its occurrence is by no means invariable, its rôle in relation to the Cochin-China diarrhœa must, as Davaine has likewise remarked, be regarded as of secondary importance. It is readily distinguished from A. stercoralis both in the adult and larval conditions. The full grown worm, although comparatively narrow, is more than twice as long as its congener; moreover, the larvæ, in place of possessing finely-pointed tails, have blunt or truncated caudal extremities. Converting M. Bavay’s millimetric measurements into fractions of the English inch, the average length of the mature worms will be about 1/11″, whilst their breadth does not exceed 1/757″ in diameter.

Ascaris mystax, Rudolphi.—This well-known helminth possesses aliform appendages, one on either side of the head. It is of a medium size, the male measuring 21/2″ and the female usually 31/2″ to 4″ in length. Both as regards the size of the alæ and the length of the body it varies in different hosts. Thus the variety infesting the dog has long been regarded as a distinct species (A. marginata), partly from the circumstance that the alæ are less conspicuous, and partly because the individuals are often longer and thicker. I possess one specimen from the dog measuring more than six inches in length. From like causes the Ascaris leptoptera and other varieties infesting the carnivora have been regarded as distinct species, but the worm also varies in one and the same host.

As remarked in my elementary treatise, the late Dr Bellingham, of St Vincent’s Hospital, Dublin, published in the 13th vol. of the ‘Annals of Natural History,’ an extended catalogue of Irish entozoa, and in this list he recorded the existence of a new round worm in man. He says of it:—“From the distinctness of the lateral membranes of the head I have given it the name of Ascaris alata.” The catalogue was constantly referred to by Dujardin, Diesing, and other systematists; but some of the continental helminthologists do not appear to have had access to Dr Bellingham’s more extended account of this parasite as given in the first volume of the ‘Dublin Medical Press,’ No. 7, Feb. 20th, 1839. I am led to this inference from the doubt which some have cast upon the very existence of the worm, although others, with more candour, supposed that Bellingham had only mistaken the species. Thus, Küchenmeister (‘Parasiten,’ s. 464, and in Lancaster’s edit., vol. ii, p. 100) says:—“The Ascaris alata, found in the small intestines of a man, is probably only a young individual of one of the long-known nematoda, if, indeed, it be a worm at all!” (The italics are mine.) This statement was reproduced by Hulme in his English edition of Moquin-Tandon’s ‘Elements of Medical Zoology,’ p. 341; and the French author himself evidently shared the doubt expressed by other people. Dujardin (‘Helminthes,’ p. 156) admitted the species, as also did Diesing (‘Systema Helminthum,’ p. 175), but the latter unluckily added the following very significant suggestion:—“An Ascaris lumbricoides capitis epidermide emphysematice inflata?”

Dr Leidy, of Philadelphia, admitted A. alata among his Entozoa hominis without comment (‘Smithsonian Contrib.’ for April, 1853), but Weinland, of Frankfort, in his list, prefixed a note of interrogation, observing also that it had been “once” found in Ireland (‘Essay on Tapeworms,’ p. 88). It is quite clear, therefore, that these authors did not believe that the Ascaris mystax was a human parasite. Those who doubtfully accepted Bellingham’s A. alata did so under the impression that whatever it was, it could not be regarded as the common Ascaris of the cat. In the new edition of Davaine’s ‘Traité,’ A. alata is, to my surprise, still retained as a separate species, and there is no mention of the occurrence of A. mystax in man. From what has recently been written by several continental helminthologists (Leuckart, Heller, and others), I rejoice to think that it is not necessary for me again to advance the really superabounding proofs that Bellingham’s A. alata was nothing more than A. mystax. It has at length been admitted by almost all who are competent to form an opinion, that the memoir originally communicated to the ‘Lancet,’ in 1863, and subsequently introduced into the text of my introductory work, finally settled the question of identity. It was through the donation of Dr Edwin Lankester and Mr Scattergood that I was enabled at the time to announce the third instance of the occurrence of this parasite in man, and since that date several other instances have been brought under public notice. Not less than seven cases have now been noticed in which this little lumbricoid of the cat and dog has been found in man. For one good human specimen I am indebted to Dr Morton. In the above list I include Heller’s specimen, and the one from Greenland sent by Steenstrup to Leuckart. According to Hering’s observations this worm grows with remarkable rapidity. Worms obtained from a puppy only six days old measured from 1/12″ to 1/6″ in length. In a twelve-day-old puppy they reached nearly an inch in length, and in a month the growth was up to four inches. Females only 11/2″ in length already contained eggs, and males only 3/4″ long had acquired their spicules. Three weeks therefore, would be amply sufficient for the completion of sexual maturity within the feline or canine host. We do not know, however, whether or not a temporary host is necessary for the larvæ prior to their introduction into the cat or dog. Hering thinks that a direct infection by the ova is sufficient; but he gives no proof of the truth of this hypothesis. “Leuckart (as quoted by Heller, l. c., s. 615) found numerous embryonal round worms in the stomach of a cat, 1/62″ in length, and in addition all the intermediate stages of growth up to the larger examples found in the small intestine. They remain in the stomach until they have attained a length of from 1/18″ to 1/12″ and then pass into the small intestine. When they have attained a length of nearly 1/8″ they cast their skins and change the tooth-like boring apparatus for the three characteristic semicircular lips. These observations on Ascaris mystax (adds Heller) render it probable that A. lumbricoides is also introduced into the human alimentary canal while still in the embryonal state or somewhat further advanced (und wohl auch grösse).” The subject will be found more fully discussed in my account of the large species further on. The cat’s worm possesses an historical interest, not only in connection with Bellingham’s original discovery, but also in respect of Nelson’s subsequent determinations as to the precise mode of impregnation in nematodes. The subject is too extended and too special to be dealt with here at any great length.

For several years after Nelson left the shores of England to spend a too short life in New Zealand, the points discussed in his ‘Edinburgh Thesis’ (and subsequently published in the ‘Philosophical Transactions’) formed the subject-matter of numerous memoirs contributed to the leading German scientific journals. Stated with brevity, it may be said that, according to Nelson, the essential act of impregnation occurs when the thimble-shaped spermatozoa of the male penetrate the unimpregnated or ovarian ovum. This, he maintained, could and did take place at any part of the surface of the unfertilised ovum, since the granular mass of which it was composed, though well defined, did not, at this period, possess a limiting—or true yolk—membrane. Professor Allen Thomson, in a series of papers (some contributed in the German language), supported Nelson’s views generally.

Fig. 49.—Germs and ova of Ascaris mystax. Nos. 1 to 3 magnified 330 diameters and Nos. 4 to 24 magnified 220 diameters. After Nelson.

Amongst Nelson’s chief opponents was Meissner, who demonstrated that the unimpregnated ova really possessed a delicate limiting membrane, and that consequently the action of the spermatozoa was restricted to that portion of the ovarian ovum which became exposed by rupture or separation from the rachis. This opening he termed the micropyle. The union of the sexual elements is quickly followed by a condensation of the yolk-granules, and by the disappearance of the hitherto centrally placed germinal vesicle. The ovum next assumes a distinctly oval shape, the true yolk-membrane and the external chorional envelope now becoming more and more differentiated, until the latter acquires a regularly tuberculated surface. Co-ordinating with these changes the granular yolk is seen transforming itself into a single large embryonal cell; after a time this cell divides and subdivides by the ordinary process of yolk-segmentation, until it is finally resolved into the condition of a short, stout, vermiform embryo. The egg having assumed its definitive oval shape, the intrachorional embryo remains coiled within the shell, and does not make its escape until the egg has passed from the body of the parent worm.

Into the question of the mode of formation of the ovarian ova, and also into that of the development of the spermatozoa, I do not enter. However unwillingly, I must, in this matter, be contented to refer to Professor Allen Thomson’s classical article ovum (quoted below), to Leuckart’s elaborate analysis (l. c., Bd. ii, s. 76–92), and also, especially, to the exhaustive memoir of Claparède, whose brilliant labors, like those of Henry Nelson, were too early terminated by death. Shortly after graduation Nelson suffered a virtually enforced banishment from his native land.

Ascaris maritima, Leuckart.—This is a well-marked species. Judging from the characters presented by the solitary, sexually-immature female which supplied Leuckart with his only means of diagnosis, this worm may be briefly described as a filariform nematode about 3/4″ in length and about 1/25″ in breadth. Although there are no cephalic aliform membranes, the cuticle immediately below the lips forms small and distinct projections, one on either side of the head (‘Die Mensch. Par.,’ Bd. ii, s. 877).

This entozoon was discovered by Dr Pfaff at Jacobshavn, near Godhavn, West Greenland, in April, 1865. Two years later he sent the specimen to Krabbe, who afterwards transmitted it to Leuckart. In the original communication addressed to the Copenhagen helminthologist, Dr Pfaff states that he procured the worm from amongst matters vomited by a child, and he incidentally observes that he had hitherto encountered only Bothriocephalus cordatus and Oxyuris vermicularis amongst Greenlanders. As to the source of infection, Prof. Leuckart not unnaturally refers to the similar conditions of existence shared by the human and carnivorous inhabitants of that country. It is well known that bears, polar-bears, seals, and walruses are largely infested by nematodes (Asc. transfuga, A. osculata, Ophiostoma dispar, &c.), but these various species are quite distinct from Dr Pfaff’s little “spulwurm.”

Ascaris lumbricoides, Linneus.—This common parasite was for a long while regarded as identical with the great lumbricoid of the horse, but the question has been finally settled by Schneider, who has shown that the human worm, although identical with Dujardin’s Ascaris suilla of the hog, is nevertheless quite distinct from the Ascaris megalocephala of solipeds. The large lumbricoid occasionally found in the ox belongs to the human worm. Our large human helminth resembles the common earth-worm in general appearance only. The males usually measure from four to six inches in length, and the females from ten to fourteen inches. Some have been reported up to seventeen or eighteen inches in length. The body is smooth, fusiform, and elastic, and marked by numerous fine transverse rings. It is attenuated towards either extremity, the anterior end terminating in a prominently three-lobed mouth The tail is bluntly pointed. The female is much shorter than the male, having a diameter of nearly a quarter of an inch. The male is supplied with a double spiculum, its tail being always more or less curved towards the central surface. The female reproductive orifice is situated above the centre of the body. According to Schneider, the tail supports from 138 to 150 caudal papillæ, that is, from 69 to 75 on either side of the median line. Below the anus the papillæ are regularly arranged in pairs, seven in number, the two uppermost pairs being double.

Notwithstanding the advantage which the size of this entozoon affords us in the matter of observation and experiment, we are yet ignorant as to the precise mode in which the young gain access to the human body. From what has been said respecting the quick growth of Ascaris mystax in the dog, and from what has been observed respecting the rapid growth of the so-called A. suilla in the hog, we know that the worm requires but a short time to pass from the larval to the sexual state. The view of Hering, Mosler, Davaine, and others, who suppose that these worms are reared in a direct manner by swallowing the ova, is, as Leuckart observed, not yet proved. We are not in full possession of the facts of larval development. It is true that Professor Heller’s interesting “find” has shown that when these worms first gain access to the human body their size is quite insignificant. At the post mortem of an imbecile, Heller discovered eighteen young worms, varying in size from about 1/9″ to 1/2″ in length (2·75 to 13 mm.). The sexes were indistinguishable. As a set-off against this, Leuckart’s repeated attempts to rear Ascaris lumbricoides and A. mystax by means of direct feeding-experiments with the eggs all failed. Thus, we are yet left in doubt as to the destiny of the larvæ during the period which elapses between the time of their escape from the egg and the time of their entry into the human body. So important is the question as to the mode of origination, growth, and subsequent development of the larvæ, that it may be well to trace, however briefly, what steps have been taken to clear up the matter. Leuckart obtained his negative results by the administration of ripe ova to dogs, rabbits, swine, and mice. The eggs of Ascaris lumbricoides have been kept alive by Dr Davaine for a period of more than five years. I have myself watched the development of their contents in fresh water through all the stages of yolk segmentation up to the stage of an imperfectly-organised, coiled, intra-chorional embryo, and have kept them in the latter condition for a period of three months. According to Davaine (‘Comptes Rendus,’ 1858, p. 1217), the fully-developed embryo is cylindrical, its length being, 1/100th of an inch. The mouth is not furnished with the three characteristic papillæ of the genus, and the tail terminates suddenly in a point. Davaine administered some of his five-year-old embryos to rats, and had the satisfaction of finding a few of these eggs in the rodent’s fæces, with their embryos still living, but striving to emerge. He also gave eggs to a cow, and introduced others into the stomachs of dogs in small linen-covered flasks. As a general result it may be said that the embryos escaped from their shells. Those eggs, however, in which the yolk-segmentation had not arrived at the early embryonal stage remained unaffected. According to Heller, the embryo of A. lumbricoides casts its first skin while still within the egg, and “a subsequent ecdysis probably completes its definitive form” (l. c., s. 615). So far back as 1853 Verloren reared coiled intra-chorional embryos in the eggs of Ascaris marginata within a period of fifteen days in distilled water. I also reared the embryos of this species in fresh water, and kept them alive for a period of nearly a year and a half, at the expiration of which time, and during the warm weather, some few of them succeeded in making their escape. According to Davaine, the eggs of many nematode species will readily retain their vitality though long exposed to dryness, but their yolk-contents will not go on developing during this period of exposure. As regards A. mystax, however, Heller remarks that whilst “the eggs have a great power of resisting external influences, their development is not arrested in spirits of wine, chromic acid, or oil of turpentine” (l. c., s. 631). In the case of Ascaris tetraptera of the mouse, embryonic formation goes on in spite of the absence of external moisture. Davaine has noticed the same thing in the oxyurides of rodents. Dryness does not even destroy the eggs of A. lumbricoides and Trichocephalus dispar. It would seem, in short, that the eggs of nematodes which normally take up their residence in cats, dogs, and in the carnivora which reside in arid regions, will develop embryos in the egg without external moisture. As before remarked, Davaine thinks it is not necessary that these nematode embryos should pass through any intermediary bearer, and he believes that they are often directly transferred to the stomach of their “hosts” whilst adhering in the form of an impalpable dust to the coats of their bearers, whence they are detached by the animal’s frequent habit of licking the fur. Davaine’s view has received some support from the observations and experiments of Unterberger with the eggs of Ascaris maculosa. This observer administered eggs of the worm to doves (whose fæces were free of eggs), and seventeen days after found ova in the fæces.

With the eggs of the Ascaris megalocephala of the horse I performed numerous experiments. I reared the embryos in simple fresh water, and found them during warm weather escaping before the expiration of five months. I also succeeded in rearing these larvæ in pond mud, noticing, at the same time, that after their escape from the shell they grew more or less rapidly up to a certain point, after which they ceased growing. The addition of horses’ dung to soft wet mud in one case, and of cows’ dung in another, neither appeared to advance nor retard the process of embryonal formation, so long as the embryos were enclosed in their shells. On the other hand, when I reared embryos in simple horse-dung purposely kept moist, they attained a higher degree of organisation than did those in wet mud or water. Having watched hundreds of these larvæ under varying conditions, I came to the conclusion that, after escape from the egg, their activity, growth, and strength was most marked when they occupied media which happened to be impure. Davaine experimented on cows, and Leuckart also experimented on horses, with the eggs of this worm without success. Leuckart also failed to rear the larvæ in intermediary hosts. Some eggs passed through the water-palmer unaltered.

These results, so far as they go, seem to be borne out by facts of a professional order. Thus, an instance has been brought under my notice where a considerable number of peasants and their children, dwelling in a parish in Yorkshire, were infested with this worm. There was, in short, a local endemic helminthiasis. Through the parish runs a stream which supplies the cottagers with all the water they employ for domestic purposes (washing, drinking, and so forth). Some of the peasants living by the side of the stream keep pigs, and the sewage from this source has been allowed to pass into the stream itself. Now, if Schneider’s determination as to the identity of the lumbricoid of man and the pig is correct (which I do not doubt), the explanation of the cause of the endemic becomes a very simple matter. But it does not explain all that we desire to know about the young worms. Either the freed embryos before they enter the human bearer accomplish further changes of form and growth in the sewage or impure water; or, what is far less probable, they pass into the bodies of intermediary hosts (such as insect-larvæ, Gammari, Entomostraca, &c.) to undergo the necessary changes. Practically, no doubt, it comes to the same thing in the end. Even if we suppose that the Ascaris suilla and A. lumbricoides are not identical species, still it is evident that any person discharging the eggs of lumbricoids in the vicinity of open waters becomes, by that fact, a source and centre of infection. To ensure an endemic it is probably only further necessary that the human inhabitants should employ the contaminated water for domestic purposes. But time and an increase of temperature must be allowed for the bringing about of those known and unknown larval changes that alike form the necessary antecedents of infection. In this connection I will only add, that if the present position of the question be such as I have here represented it to be, we see that Mosler was not far wrong when he suggested that “contamination of the drinking water with the eggs out of privies is to be blamed” as a source of infection. According to Heller, from whom I quote, Mosler actually demonstrated the presence of the eggs in water thus exposed. In like manner it becomes obvious that Davaine’s practical remark (although it was based on the assumption of a direct infection by the eggs), that filtration will probably be sufficient to prevent infection, loses nothing of its hygienic value.

The foregoing observations naturally lead one to the question of frequency and distribution. Davaine holds that the comparative infrequency of this parasite in Paris is due to the free use of the filter. In London, though not uncommon, the worm rarely occurs in great numbers in one bearer. Those cases in our hospitals, where considerable numbers have been present, have usually come up from suburban or country places. Heller states that these worms were found in 9·1 per cent. of post mortems conducted at Dresden, in 12 per cent. at Erlangen, and in 17 per cent. at Kiel. He quotes Huss as stating that no one is free from this worm in Finland. The prevalence of large round worms in warm countries generally is well known. Throughout India and the East they are extremely abundant, and the same may be said of the West Indies, Brazil, and the adjacent territories. Professor Dyce and others have remarked on the extreme prevalence of lumbrici in the Mauritius, but they are comparatively rare along the sea border. In all situations where there is an abundant fresh-water supply these parasites are particularly common, as in the lowlands of Holland and the lake districts of Sweden. The abundance of water is certainly not alone sufficient to explain the frequency of the parasite, seeing that the most important factor is that which rests upon the uncivilised habits of the rural population. What, therefore, it may be asked, can be the cause of immunity enjoyed by Icelanders in this respect? The answer is not apparent; nevertheless Krabbe and Finsen have testified to the fact that Iceland is the only country that is entirely free from Ascaris lumbricoides.

As remarked in my previous work the number of worms present in any human bearer is usually small, varying commonly from one to six or eight. Cases in which scores or hundreds have existed are comparatively rare. Küchenmeister mentions the case of one child who passed 103 examples, and of another child that harbored from 300 to 400 worms. Dr Gilli, of Turin, gives a case where 510 were passed by a child, and Cruveilhier estimated that over 1000 existed in an idiot girl, whose intestines he found crammed with them. A remarkable case has also been communicated to me by Dr Mackeith, of Sandhurst, Kent, who, by means of santonine, expelled from a little girl, five and a half years of age, 300 lumbrici; and I am likewise indebted to Dr Cooper Rose for notes of a case in which about thirty lumbrici were expelled, chiefly in consequence of the employment of this drug. The most interesting fact, however, in this case was that the child was only fifteen months old. In this case the symptoms were severe.

The proper habitat of the lumbricus is the upper and middle part of the small intestine. From this situation it often wanders into the stomach, and frequently gains access to the outer world, not only by the natural passages of the mouth, nostrils, and anus, but also, occasionally, in a more direct way, by perforating the intestinal and abdominal walls. Many cases are on record where lumbrici have passed into the abdominal cavity. In other instances they have lodged themselves within the abdominal viscera and pulmonary organs. When they find their way into the parietes of the abdomen and adjacent parts, they usually give rise to the formation of abscesses requiring surgical interference.

As regards the symptoms produced by lumbrici, these vary according to the situation they happen to occupy. The symptoms are also modified by age and temperament. In the stomach and intestines they give rise to colic and shooting pains about the abdomen, followed generally by dyspepsia, nasal itching, nausea, vomiting, and even diarrhœa. Occasionally death supervenes suddenly. A singular case of this kind (the particulars of which I only gathered from a local newspaper) occurred in a boy, thirteen years of age, at the County Gaol at Hertford, in 1873. From Dr Evans’s statement, made at the coroner’s inquest, the sole cause of death appeared to be due to pressure on the windpipe by a worm lodged in the gullet. Sometimes there is cerebral disturbance, attended with general restlessness and convulsive twitchings during sleep. Thus, Dr Woodman has recorded a serious case of convulsions arising from lumbricoid worms, in which, however, a cure was effected by expulsion of the worms. An anonymous writer in the ‘Medical Gazette’ records a case of epilepsy from this cause, whilst another writer in the same journal (1839) mentions an instance where two lumbrici and one tapeworm were associated in the production of similar phenomena. But a much more striking case is also given (anonymously) in the ‘Gazette’ for 1874 (p. 415), where a single lumbricus caused the bearer to be a lunatic for eight years. The victim suffered from cataleptic fits, which lasted for two or three weeks at a time. M. Petrequin, in his ‘Traité Pratique,’ records two cases of amaurosis in young girls produced by lumbrici. A fatal case is recorded by Petrenz, where 200 worms produced enteritis, and another fatal case is given by Roger from perforation (1848). Cases of perforation are also given by Young, by Blair (1861), by Mondière (1839), by Buchner (1851), by Sheppard (1861), and by Luschka (1854), the worms in this last-mentioned case occupying the cavity of the pleura. Cases of severe irritation affecting the genito-urinary organs are given by Dreyfus, Buckingham, and others; and one or two instances are reported where these worms have been discharged from several parts of the body (Neilson, 1833). I may add that the third fasciculus of a work illustrating the collection of morbid anatomy in the Army Medical Museum at Chatham gives a case of lumbrici occupying the biliary ducts and gall-bladder. I find, moreover, two additional cases of perforation of the small intestine, one of which appeared in the ‘London Medical Gazette’ (1827) and the other in the ‘Lancet’ (1836).

During the Franco-German war Dr Reginald Pierson, as he afterwards informed me, removed a lumbricus from an abscess formed in the abdominal parietes of a soldier. But amongst the most curious cases (illustrating the wandering habits of these parasites) are those severally described by Barwell (1857), Williams, Prichard, and the Messrs Stockbridge. In Barwell’s case an Ascaris was expelled from a child who had swallowed the brass “eye” of a lady’s dress. Through the circular loop of this eye, used as a toy, the Ascaris had partly thrust its body, and becoming thus strangulated, it probably perished before it was evacuated. In Prichard’s case (1859) one or two lumbrici had similarly trapped themselves in the eyes of buttons swallowed by the patient, and one worm, not contented with a single strangulation, had succeeded in passing its body through two buttons. In 1842 Mr T. G. Stockbridge gave a similar case, in which he, not inaptly, spoke of these “hooks and eyes” as constituting a new remedy or “worm-trap” for lumbricus, and singularly enough, a namesake (W. Stockbridge), in the succeeding year, also recorded a like instance of the “mechanical expulsion of worms” by metallic buttons. Again, a third correspondent in the ‘Boston Journal,’ under the initials A. M., spoke of an open-topped thimble as constituting another new “worm-trap,” whilst he gave a case of lumbrici penetrating “metallic suspensor buttons.” There is also the case reported by Williams, who, at a meeting of the Boston Society for Medical Improvement, exhibited “a lumbricus with a dress-hook attached” (1857). Lastly, another lumbricus, trapped in the same way, may be seen in the Museum of the Royal College of Surgeons at Edinburgh.

Owing to the presence of a peculiar irritating vapour which is given out by these lumbricoids, particularly when fresh, several observers have experienced curious symptoms. Thus, Miram on two occasions, when examining A. megalocephala, was attacked with sneezing, excessive secretion of tears, with swelling of the puncta lacrymalia, and Huber also experienced a troublesome itching of the hands and neck after examining specimens of A. lumbricoides. In like manner I have myself had watery suffusion of the eyes (when collecting the perivisceral fluid for Marcet’s analyses: see Bibliog.), and Bastian has given a detailed account of the serious effects which the poison produced upon him. In Bastian’s case even spirit specimens produced irritation. The attacks of catarrh and asthma were so persistent and severe that they lasted for six weeks at a time. So sensitive was Bastian to the lumbricoid-miasm that he could not even put on a coat that he had worn during his investigations without experiencing fresh attacks of sneezing and other catarrhal symptoms. The attacks became periodical, occurring between five and six in the morning, being accompanied by dyspnœa and a distressing spasmodic cough. Bastian, in short, was quite a martyr in the cause of nematode anatomy.

Bibliography (No. 34).—Abousson, L., “On the Presence of Worms (lumbrici) in the Air-passages,” from ‘Arch. Gén. de Méd.,’ in ‘Med.-Chir. Rev.,’ 1836.—(Anonymous), A. M., “Another New Worm-trap—an open-topped Thimble in the Nostril (also notice of metallic suspender buttons penetrated by Lumbrici),” ‘Bost. Med. and Surg. Journ.,’ vol. xxvii, p. 121, 1842–43; see also T. G. and W. Stockbridge.—(Anon.), “Lumbrici expelled by Bismuth,” ‘Bost. M. and S. Journ.’ (from ‘Gaz. des Hôp.,’ ‘Journ. des Connaiss. Méd.,’ and ‘Boletin del Inst.-Med.-Valenc.’), 1859.—(Anon.), “Case of one Tapeworm and two Lumbrici causing Epilepsy,” from ‘Bull. du Midi’ and ‘Gaz. Méd.,’ 1839.—(Anon.), “Case of Perforation of the Ileum by Ascarides,” from ‘Hufl. and Ossan’s Journ.,’ in the ‘Lancet,’ 1836.—(Anon.), “Case of Lumbrici in the Biliary the Ducts and Gall-bladder,” note and fig. in third fasc., illust. the Coll. of Morb. Anat. in the Army Med. Mus. at Chatham, 1838.—(Anon.), “A Lumbricus causing Catalepsy, with Fits lasting two or three weeks; Cure by Vomiting,” ‘Lond. Med. Gaz.,’ 1847, p. 415.—Archer, E., “On a Case of A. lumbricoides producing alarming symptoms,” ‘Lancet,’ 1857.—Barwell, “Case of Ascaris expelled by the swallowing of a foreign body,” ‘Lancet,’ 1857.—Bastian, H. C., “On the Anatomy and Physiology of the Nematoids, Parasitic and Free,” ‘Phil. Trans.,’ 1866, p. 545; for the account of his poison-symptoms, see footnote, p. 583.—Batterbury, R. L., “Jaundice due to the presence of Lumbrici,” ‘British Med. Journ.,’ Nov., 1878, p. 721.—Bigelow, H., “Worm in an Abscess,” ‘Bost. Med. and Surg. Journ.,’ vol. xxxiii, p. 486, 1836.—Blatchley, C. C., “Two Cases of A. lumbricoides, attended with Abscesses, followed by large purulent discharges, and Worms therein,” ‘New York Med. and Phys. Journ.,’ vol. i, new series, p. 209, 1829.—Bonfils, E., “Lesions and Path. Phenomena caused by Lumbrici in the Biliary Ducts,” from ‘Arch. Gén.,’ in ‘Brit. and For. Med.-Chir. Rev.,’ 1858, and in ‘Amer. Journ. of Med. Sci.,’ vol. xxxvii, 1859.—Bradford, J. T., “Singular Case of Worms (Lumbrici),” ‘Bost. Med. and Surg. Journ.,’ vol. xxviii, 1843.—Brigham, A., “Worms in the Bladder simulating ‘Stone,’” ‘Amer. Journ. Med. Sci.,’ 1837; ‘Med.-Chir. Rev.,’ 1837; ‘Quart. Journ. Calcutta Med. and Phys. Soc.,’ vol. ii, p. 132, 1838.—Buchner, “On the Perforation of the Intestinal Canal by Worms (with ref. to two cases),” from ‘Med. Zeitung,’ 1850, in ‘Med.-Chir. Rev.,’ 1851.—Calderwood, “Treatment,” ‘Brit. Med. Journ.,’ Jan. 30, 1875.—Chapman, N., “Case of 68 Ascarides causing Pulmonary Disease,” in his ‘Dis. of the Thoracic and Abd. Viscera,’ p. 263, and in ‘Med.-Chir. Rev.,’ 1845.—Chiaje, Delle-, in ‘Rend. dell’ Accad. di Napoli,’ 1846 (“Anat.,” p. 403).—Church, J., “On A. lumbricoides,” ‘Mem. Med. Soc. Lond.,’ vol. ii, 1789.—Claparède (l. c., Bibl. No. 33, for development).—Clark, P., “Discharge of a Lumbricus through the Male Urethra,” ‘New York Journ. Med.,’ 1844, rep. in ‘Lancet,’ 1844, and in ‘Edin. M. and S. Journ.,’ vol. lxiv, 1845.—Cloquet, ‘Anat. des vers Intest.,’ 1824.—Cobbold, “On Sewage and Parasites, especially in relation to the Dispersion and Vitality of the Germs of Entozoa,” ‘Med. Times and Gaz.,’ Feb. 25, 1871, p. 215.—Idem, ‘Entoz.,’ p. 302–315.—Idem, ‘Worms,’ lect. xvi, p. 3.—Idem, art. “Ascaridæ,” in ‘Maunder’s Treasury,’ 1862.—Colvan, J., “Case in which Eleven Round Worms of the species A. lumbricoides were removed by Anthelmintics,” ‘Dubl. Med. Press,’ vol. xxvi, p. 211, 1851.—Cutler, J. H., “Death by Worms (a large Lumbricus being found in the Wind-pipe),” ‘Bost. Med. and Surg. Journ.,’ vol. lxvi, p. 392, 1862.—Czermak, in ‘Sitz. d. k. Akad. d. Wissensch.,’ 1852 (“Anat.,” s. 755).—Davaine, in his ‘Traité,’ l. c., 2nd edit., syn. xcvii, and p. 122–235 (with details of forty-five cases); see also his memoir “On the Development and Propagation of the Trichoceph. dispar and A. lumbricoides,” from ‘Comptes Rendus,’ in ‘Ann. Nat. Hist.,’ vol. ii, 3rd series, 1858; also in the ‘Journ. of Pract. Med. and Surg.,’ Eng. edit., vol. i, 1858, and in the ‘Veterinarian,’ vol. xxxii, p. 700, 1859, from ‘Proc. of Acad. des Sci.,’ in ‘Bost. M. and S. Journ.,’ vol. lix, p. 157, 1858–59.—Idem, art. “Entozoaires,” in ‘Dict. de Méd. et Chir. prat.’—David, J. B., “Cases of Perforation of the Intestines by Worms,” from ‘Gaz. Méd. de Paris,’ in ‘Dubl. Med. Press,’ 1840, p. 223.—Diesing, ‘Syst. Helm.,’ ii, p. 166; and in ‘Revis der Nemat.,’ l. c., s. 660.—Douglas, J., “Worms (Lumbrici) evacuated at an Ulcer of the Groin,” ‘Med. Ess. and Obs.,’ vol. i, 2nd edit. (vol. i, 5th edit., p. 179), p. 222, 1737.—Dowler, B., “Case of Worms in the Urinary Bladder,” from ‘New Orl. M. and S. Journ.,’ in ‘New York Journ. Med.,’ new series, vol. xiv, 1855.—Dubini, ‘Entozoografia umana’ (“Anat.,” p. 148).—Dupuytren, “Lumbricus passed by the Urethra,” from “Clin. Lect.,” in ‘Lond. Med. and Surg. Journ.,’ 1846, p. 14.—Dyce, R., “On Lumbrici and the Causes of their Prevalence in the Mauritius,” ‘Lond. Med. Gaz.,’ 1834.—Evans, T., “Lumbricus causing Death,” rep. of coroner’s inquest in the ‘Herts Advertiser and St Alban’s Times’ for Feb. 8, 1873.—Gervais (and Van Beneden), ‘Zool. Med.,’ ii, p. 118.—Gilli, “Account of a Case in which 510 Worms (Lumbrici) were voided by a Child,” from ‘Giorn. d. Scienze Med. di Torino,’ in ‘Med.-Chir. Rev.,’ 1843.—Goopta, G. D. D., “On Suicide and Lumbrici,” ‘Ind. Med. Gaz.,’ July, 1874, and ‘Lond. Med. Rec.,’ Aug., 1874, p. 502.—Heller, A., “Darmschmarotzer,” in Von Ziemssen’s ‘Handb.,’ s. 612–631.—Holland, G. C., “A peculiar Case of Nervous Disease or Derangement of the Nervous System (associated with A. lumbricoides),” ‘Edin. M. and S. Journ.,’ vol. lxiii, 1845.—Howall, “Abscess of the Groin, with discharge of Lumbrici,” ‘Lond. Med. Gaz.,’ 1845, and ‘Edin. M. and S. Journ.,’ 1846, p. 241.—Johnson, W. G., “Case of forty Lumbrici in a Boy who died with Traumatic Tetanus,” “Rep. of South Mid. Br. of Brit. Med. Assoc.,” in ‘Brit. Med. Journ.,’ 1858.—Kell, “Perforation of the Intestines by a Worm,” ‘Lond. Med. Gaz.,’ 1828.—Kilgour, T., “Case in which Worms in the Nose, productive of alarming Symptoms, were removed by the Use of Tobacco,” ‘Med. Comment.,’ vol. viii, 1783.—Kirkland, “Case of Lumbricus in an Abscess of the Liver,” rep. in his book, entitled ‘An Enquiry,’ vol. ii, p. 186 (quoted by Richter and Davaine), London, 1786.—Küchenmeister, ‘Manual,’ Eng. edit., p. 410–427.—Leidy, J., ‘Proc. Acad. Phil.,’ 1856, p. 50.—Lente, F. D., “Lumbricus in the Stomach causing Dyspnœa,” in his “Rep. of Cases occurring in the New York Hosp.,” in ‘New York Journ. of Med.,’ vol. v, new series, p. 167, 1850.—Lettsom, “Case of Lumbricus evacuated from an Abdominal Abscess,” ‘Trans. Med. Soc. Lond.,’ and ‘Lond. Med. Repos.,’ 1817.—Leuckart, l. c., s. 152–258.—Lieberkühn, in ‘Miller’s Arch.’ (“Anat. of A. suilla”), 1855, s. 331.—Luschka, “Case of Lumbrici within the Pleura,” from ‘Virch. Arch.,’ in ‘Med.-Chir. Rev.,’ 1854.—Lowne, B. T., “The Anatomy of the Round Worm,” ‘Trans. Roy. Micr. Soc.,’ 1871, p. 55.—Maesson, “On a Worm found in the Bubo of a Woman 36 years of age;” see ‘Entozoa and Parasites, being a ref. to numerous papers;’ from “Valentin’s Repertorium,” in ‘Month. Journ. of Med. Sci.,’ vol. ii, p. 559, 1842; also in ‘Micr. Journ. and Struct. Rec.,’ p. 85, 1842.—Marcet, W., “Chemical Exam. of the Fluid from the Peritoneal Cavity of A. megalocephala,” ‘Proc. Roy. Soc.,’ 1862, No. 72, p. 69.—Martin, D. T., “Large number of Worms (140 examples of A. lumbricoides) discharged from a Child five years old,” rep. from the “Stethoscope,” in ‘Bost. Med. and Surg. Journ.,’ vol. xliv, p. 301, 1851.—Mattei, R., “On a Case of two Lumbricoid Worms, which had penetrated during life into the liver, and were demonstrated by Prof. G. Pelizzari to his pupils in the Sch. of Path. Anat. of Florence,” from ‘Gaz. Med. Ital. Toscana,’ in ‘Dubl. Quart. Journ.,’ vol. xxiv, 1857.—Michel, “Case of Epilepsy in a Girl ten years of age, caused by Lumbrici,” from ‘Journ. des Connaiss. Méd.,’ in ‘Amer. Journ. of Med. Sci.,’ vol. vi, p. 451, 1843.—M’Laggan, J., “Gangrenous Sore from a large Worm in the Parietes of the Abdomen,” ‘Med. Comment.,’ vol. ii, 1774, p. 80.—Molin, in ‘Sitzungsb. d. k. Akad.,’ 1859, s. 23.—Mondière, “On Perforation by Worms (three cases),” from ‘L’Expérience,’ in ‘Med.-Chir. Rev.,’ 1839.—Moore, E. D., “Example of A. lumbr. ejected by the Mouth,” ‘Prov. Med. and Surg. Journ.,’ 1852.—Morgan, J., “Case of Perforation of the Stomach, probably by a (Lumbricus) Worm,” ‘Lancet,’ 1836.—Morland, W. W., “Ejection of numerous Lumbrici from the Mouth, impaction of the small intestine with Lumbrici, (of which 365 were removed post mortem),” ‘Bost. M. and S. Journ.,’ vol. lvi, 1857.—Idem., an “A. lumbr. of unusual size (over 17 inches long),” ‘Rep. of Bost. Soc. for Improv.,’ in ‘Bost. M. and S. Journ.,’ vol. lviii, p. 62, 1858.—Neilson, “Discharge of Worms from various parts of the Body,” ‘Med.-Chir. Rev.,’ and ‘Lond. Med. Gaz.,’ 1833.—Omond, R., “Case of Lumbricus attended with Hæmoptysis,” ‘Edin. Med. Journ.,’ 1856.—Owen, R., art. “Entozoa,” l. c.—Padley, G., “Jaundice and Lumbrici,” ‘British Med. Journ.,’ Dec. 14, 1878, p. 877.—Petrenz, “Case of fatal Enteritis produced by (200) Lumbrici,” from ‘Clarus and Radius’ Beitr. zur Pract. Heilk.,’ in ‘Dubl. Journ.,’ vol. xi, 1837; also in ‘Lond. Med. Gaz.,’ 1837.—Playfair, “Case of Lumbricus (69 specimens) cured by the Mudar,” ‘Calc. Med. and Phys. Soc. Trans.,’ vol. ii, p. 407, 1826.—Pomeroy, C. G., “Escape of Worms (17 Lumbrici) from the Navel of a Child,” ‘Bost. M. and S. Journ.,’ vol. xxi, 1840.—Prichard, A., “Case of Lumbricus,” ‘Rep. of East York and North Lincoln Br. of Brit. Med. Assoc.,’ in ‘Brit. Med. Journ.,’ 1859.—Royer, “Case of Intestinal Perforation by a Lumbricus,” report in ‘Lancet,’ 1856.—Rumsey, N., “Cases of Lumbricus and Tænia associated with Hæmoptysis,” ‘Med.-Chir. Trans.,’ 1818.—Sandwith, H., “Remarks on Worms in the Peritoneal Cavity, with a case,” ‘Brit. Med. Journ.,’ 1861.—Schleifer, “Case of a Deaf and Dumb Child restored after the discharge of Worms (87 Lumbrici and innumerable Oxyurides),” from ‘Œsterr. Med. Wochensch.,’ in ‘Amer. Journ. of Med. Sci.,’ vol. viii, p. 473, 1844.—Schneider, A., ‘Monog. der Nemat.,’ s. 36.—Idem, “On the Nervous System of Nematoda,” from the German by Busk, ‘Quart. Journ. Micr. Sci.,’ 1863.—Schultze, “Case of Stuttering occasioned by Worms,” from ‘Med. Zeit.,’ in ‘Med.-Chir. Rev.,’ 1837.—Sheppard, “Case of A. lumbr. extracted from an Abdominal Abscess,” ‘Brit. Med. Journ.,’ 1861.—Smith, J. N., “Thirty-nine Specimens of Ascaris lumbricoides in a Child,” ‘Bost. M. and S. Journ.,’ 1856.—Spalding, P., “Case of Worms (100 Lumbrici),” ibid., 1839.—Stockbridge, T. G., “Worm-trap (hooks and eyes), a New Remedy,” ibid., vol. xxvii, p. 73, 1842–43; see also Anon., A. M.—Stockbridge, W., “Mechanical Expulsion of Worms (by metallic buttons),” ibid., vol. xxviii, p. 419, 1843.—Van Beneden, ‘Animal Parasites,’ l. c., p. 95; see also Gervais.—Villemin, “Case of Death from Worms (about 18 specimens of A. lumbr.),” from ‘L’Union Méd.,’ in the ‘Lancet,’ and rep. in ‘Dubl. Med. Press,’ vol. xxxv, p. 327, 1856.—Weinland, in his ‘Essay,’ l. c., p. 88, and in ‘Troschel’s Arch.,’ 1859, s. 283.—Welsh, T., “Curious Facts respecting (symptoms produced by) Worms (A. lumbricoides),” art. ix in the ‘Med. Papers communicated to the Massachus. Med. Soc.,’ vol. i, p. 87, 1790.—Wendelboe, “Case of discharge of Worms (Ascarides?) through the Skin,” from ‘Rep. of Roy. Soc. Copenhagen,’ in ‘Lancet,’ 1836; see also Neilson.—Williams, H. W., “Exhibition of a Lumbricus with a dress-hook attached,” ‘Rep. of Bost. Soc. for Med. Improv.,’ in ‘Bost. M. and S. Journ.,’ vol. lvi, p. 163, 1857.—Wilson, J., “On the prevalence of Lumbrici in China,” in his ‘Med. Notes on China,’ London, 1846.—Woodman, W. B., “Case of Convulsions, &c., arising from Lumbricoid Worms,” ‘Med. Times and Gaz.,’ 1863.—Young, W., “Cases in which Lumbrici were evacuated by Ulceration through the Parietes of the Abdomen,” ‘Lond. Med. Gaz.,’ from ‘Glasgow Med. Journ.,’ 1828; rep. in ‘Lond. Med. and Surg. Journ.,’ vol. i, p. 564, 1828.

SECTION IV.—Part I.—Acanthocephala (Thornheaded worms).

Echinorhynchus gigas, Goeze.—There is but one recorded instance of the occurrence of this entozoon in the human body. This is the oft-quoted case by Lambl, given in the ‘Prager Vierteljahrschrift’ for 1859. Lambl, indeed, described it as a separate species (E. hominis), but as the worm was a sexually-immature female, its identification with E. gigas, notwithstanding Schneider’s great authority, can hardly be regarded as absolutely certain. The worm was found in the small intestine of a boy of nine years, and measured only rather more than the fifth of an inch in length. As Leuckart hints, the worm may be Echinorhynchus angustatus, or possibly the E. spirula, a species found in various South American apes (Cebus and Jacchus), and also in the Barbary ape (Inuus).

In 1872, Welch, unaware of Lambl’s case, announced the discovery of “the presence of an encysted Echinorhynchus in man.” The minute parasite found by him occurred in a soldier, thirty-four years of age, who died at Netley, but who had contracted the worm in India. “It was situated in the jejunum, immediately beneath the mucous coat, and formed an oval prominence in the interior of the gut.” Speaking with great confidence, this able microscopist further remarks:—“The character and arrangement of the hooklets unequivocally shadowed forth a species of Echinorhynchus for the first time discovered as a representative of the Acanthocephala in the human body.” Along with his elaborate description Welch gives several figures; but these, so far from producing conviction as to the accuracy of his inferences, have unfortunately led me to believe that the parasite in question would be more properly referred to the Pentastomidæ. But for Heller’s acquiescence I might have more fittingly noticed this worm elsewhere. Davaine falls into the same view, and moreover accepts Lewis’s “Echinorhynque du Chien,” which I have shown to be a nematode (Cheiracanthus robustus). It is thus that serious errors creep into the literature of parasitism.

In the adult state the female Echinorhynchus gigas is a huge species, occasionally reaching two feet in length, with a breadth of one third of an inch. The male rarely exceeds three inches. This worm is common in swine, both wild and domesticated. According to Schneider the embryos take up their residence in the grubs or larvæ of the cockchafer (Melolontha vulgaris), a discovery which very readily explains the manner in which hogs become infested. Whether E. gigas be a human parasite or not, it is certainly very injurious, not to say destructive, to swine. Although this parasite must be quite common in England I have experienced great difficulty in procuring specimens. In the second book of this work I shall give some interesting particulars furnished by the memoir of Prof. Verrill and privately by Mr George Wilkins. (See ‘Parasites of the Pachydermata’.)

As explained in the Introduction we must regard the Leeches and many allied forms of Suctorial Annelids as creatures possessed of semi-parasitic habits. They are, perhaps, something more than what Van Beneden styles “free parasites”—an expression which almost looks like a contradiction of terms. I cannot here, however, stop to discuss questions which lie, as it were, on the border-land of parasitology. Three species of leech are more or less commonly employed in medicine. These are the grey leech (Sanguisuga medicinalis, Savigny), the green-leech (S. officinalis, Sav.), and the dragon-leech (S. interrupta, Moq.-Tandon). The two former abound in Central and Southern Europe, being also present in North Africa, the last named inhabiting Barbary and Algeria. So abundant are leeches in the country bordering the Mediterranean that during the invasion of Egypt by Napoleon the French soldiers suffered seriously from their attacks. When the men lay down to drink, the leeches (Hæmopis sanguisorba, Sav.) affixed themselves to their mouths and nostrils, producing serious distress. They also attacked horses, camels, and cattle. In like manner the Ceylon and Philippine Island leeches (S. ceylonica, Moq.-Tand., or S. tagalla, Meyen), of which there are several varieties, prove exceedingly troublesome to Europeans. These leeches, not being aquatic forms, occupy woods and damp places. Unless the limbs of travellers are well protected, the presence of the blood-suckers is soon discovered by the trickling of blood from the limbs and lower part of the body. The leeches even sometimes creep up to the neck and other adjacent parts. These “free parasites” also attack horses, causing much loss of blood. Terrestrial leeches abound more or less in all warm countries. Sir J. Hooker encountered them in the Himalayas, and they are common in China, Japan, Java (S. Javonica, Wahlberg), and other eastern parts. They likewise abound in Brazil and Chili. The American leeches for the most part belong to the genus Hæmenteria (H. Mexicana, H. officinalis, and H. Ghiliani, Filippi). The last named is common in Brazil, the other two being Mexican forms. Another species, which is blind, has been found in Brazil by F. Müller (Cyclobdella lumbricoides). Not only the above-named species, but also many other kinds of leeches are in the habit of attacking man and the domestic animals, but the subject is too extended and special to be fully dealt with in this work. Almost a legion of species are known as externally parasitic upon Fishes, Chelonian and Batrachian reptiles, Crustaceans, and Echinoderms.

SECTION IV.—Part I.—Acanthocephala (Thornheaded worms).

SECTION IV.—Part II.—Suctoria (Leeches)