Flukes are rare in swine; nevertheless, Fasciola hepatica and Distoma lanceolatum are occasionally present in the domestic hog, and the peccaries (Dicotyles) are infested by an Amphistome (A. giganteum). This large species, 3/4″ in length, formed the basis of an admirable account of the anatomy of this genus of worms which the learned Vienna helminthologist, Diesing, wrote before he was deprived of his eyesight. The merits of that respected systematist’s investigations have, I think, been much underrated, in consequence, no doubt, of the artificial character of his system of classification. For all that, his writings remain invaluable. Turning to the cestodes of swine, there is not, so far as I am aware, any evidence of the occurrence of sexually-mature tapeworms either in the hog or its allies; but the frequency of larval cestodes, known as measles (Cysticercus telæ cellulosæ), was well known to the early Jewish writers. In the first part of this work I devoted as much space as I could spare to the consideration of Cysticerci in general, and the pork-measle in particular; but an exhaustive knowledge of the subject in relation to hygiene can only be acquired by consulting the principal original memoirs (quoted in the Bibliographies Nos. 13 and 14). In a Westphalian ham, part of which was sent to me for examination, I calculated that each pound of the flesh must have contained upwards of 600 Cysticerci. I was informed by the donor, Dr Prior, that in spite of the disgusting state of the meat much of it had been eaten by the well-to-do family who purchased the ham. Cysticerci occasionally occupy the brain of the pig in considerable numbers. Florman recorded a case of this kind where their presence gave rise to vertigo in all respects resembling the gid ordinarily produced by Cœnurus in the sheep. As regards the larger cestode larvæ, Cysticercus tenuicollis and Echinococcus veterinorum are of frequent occurrence. One not unfrequently encounters the former in the mesentery, whilst the liver of the hog is sometimes so crowded with hydatids that scarcely any of the glandular substance of the organ remains visible. It is surprising how little the infested bearers appear to be inconvenienced in such cases. In the winter of 1859, and in the autumn of 1860, I found large cystic entozoa in an African Wart-hog and in a Red River hog. These animals had died at the London Zoological Society’s Menagerie; and as the worms appeared to me at the time to be quite distinct from the ordinary slender-necked hydatid, they were named, respectively, Cysticercus phacochæri æthiopici and C. potamochæri penicillati. The solitary example from the wart-hog was found in a cyst near the colon; whilst of the five large bladder-worms obtained from the Red River hog, one infested the liver and the other four were lodged in the folds of the mesentery. The caudal vesicle of the worm from the wart-hog measured 31/2″ in diameter, the vesicle of the other bladder-worm being much longer. A reference to the original figures will show that these forms are distinct. Swine are largely infested by nematodes. The best-known form is Ascaris lumbricoides, which Dujardin regarded as distinct (A. suilla). The hitherto disputed identity of this worm with the human lumbricoid being no longer questionable, the importance of the entozoon in relation to lumbricoid endemics must at once be obvious; I have already, however, dwelt upon this subject when treating of the human parasites. In like manner, the subject of the flesh-worm disease, which is due to Trichina spiralis, cannot be discussed in this place, as I have fully entered upon it in connection with trichinosis in the human subject. What may be the nature of the small threadworms found by Leidy in the extensor muscles of the hog I cannot say, but Diesing inferred that they might represent a distinct species (Trichina affinis). As regards the allied genus Trichocephalus, the common species infesting swine (T. crenatus), appears to be rarely absent. It not only infests the common domestic and wild hog, but the peccaries and wart-hogs. These entozoa are probably harmless to their bearers. In reference to them Krabbe says:—“When the eggs are expelled with the excrement and pass into water, then the embryos, after several months’ furlough, and there undergoing further development, are transferred to the swine’s intestinal canal.” If I rightly understand the paragraph (‘Husdyrenes Indvoldsorme,’ p. 28), Krabbe states that the embryos are still within their egg-coverings when infection takes place. The maw-worm of the hog is known as Spiroptera strongylina. It was described and figured by Gurlt. The males measure 1/2″ and the females 3/4″ in length. Specimens of this worm were supposed to have been found by Natterer in Dicotyles albirostris; but it seems that the worms in question represent a distinct species, if not an altogether new genus. In the year 1864 Professor Simonds placed in my hands a very singular nematode, to which I gave the binomial term Simondsia paradoxa. Numerous examples of this worm were found by Prof. Simonds occupying cysts within the walls of the stomach of a hog which had died at the London Zoological Society’s Menagerie. In my introductory treatise I wrote of it as follows:—“The worm in question has been regarded by Mr Simonds as a species of Strongylus, but I am inclined to think that its affinities will place it nearer to the genus Spiroptera. At present I have only examined the female, which is characterised by the possession of a multitude of large tentacle-like appendages surrounding the neck. These processes, by their aspect, remind one of the so-called branchial projections on the back of Eolis, but in this worm I believe them to be special folds formed for the lodgment of unusually developed uterine organs. The female worm is about 3/4″ in length.”

In the interval that has elapsed I have been unable to supply further particulars, and unfortunately the original drawings of the worm have been lost. The habits of the parasite remind us of Spiroptera megastoma infesting the walls of the stomach of the horse. Not improbably this singular entozoon may turn out to be identical with Molin’s Spiroptera sexalata, and if so, it may correspond with Spiroptera strongylina. However, Diesing afterwards recognising, as I had done, the desirability of separating this last-named worm from the Spiropteræ proper, formed for it his new genus Physocephalus. He then called the worm Physocephalus sexalatus. If, as is probable, my Simondsia and Diesing’s Physocephalus are identical, the species found by Simonds ought to be recognised by the generic title which Diesing proposed. His genus was established about four years before I described my Simondsia. Diesing was evidently led up to the recognition of the generic distinction of the worm by Molin’s examination and description of the worm. As, in my original account of the worm found by Simonds, I spoke of numerous appendages to the neck, it is evident that further investigation is necessary to clear up the question of identity. According to Molin and Diesing the male Spiroptera sexalata measures rather beyond 1/4″ and the female beyond 1/2″ in length. Neither Diesing nor Molin speak of Natterer’s worms as being found encysted. In fact they were free. Molin simply remarks:—“Io ne esaminai in oltre 6 esemplari maschi e 77 femine raccolti in parte dal muco che revestiva le pareti dello stomaco, ed in parte dal pasto contenuto nello stesso organo di un Dicotyles albirostris femina ai 24 Aprile, 1826.” After all that has been said it may be that my Simondsia paradoxa and Diesing’s Physocephalus sexalata are quite distinct, and that like the large- and small-mouthed maw-worms of the horse (Spiroptera megastoma and S. microstoma) they play a corresponding rôle. Before very long I hope to set this question definitively at rest.

Passing to the strongyloid nematodes one of the most remarkable and important species is Stephanurus dentatus. In the ‘Annalen des Wiener Museums’ for 1839 (s. 232) this worm was first described by Diesing, who employed the generic title as expressive of the crown-like figure of the tail of the male worm. Diesing wrote as follows:—“At Barra do Rio Negro, on the 24th of March, 1834, Natterer discovered this peculiar genus of worms occurring singly or several together in capsules situated amongst the layers of fat in a Chinese race of Sus scrofa domestica. The males measure from ten to thirteen lines long, the females from fifteen to eighteen lines, the former being scarcely a line in breadth at the middle of the body, whilst the latter are almost a line and a half in thickness. The curved body thickens towards the tail, is transversely annulated, and viewed with a penetrating lens is seen to be furnished with integumentary pores. The oral aperture opens widely. It is almost circular, and is supplied with six teeth at the margin. Two of these standing opposed to one another are larger and stronger than the rest. The tail of the male, when spread out evenly, is surrounded by a coronet of five lancet-shaped flaps; the combined flaps being connected together from base to apex by means of a delicate transparent membrane. The single spiculum situated at the extreme end of the tail projects slightly forward and is surrounded by three skittle-shaped bodies. The tail of the female is curved upon itself, rounded off, and drawn out at the extreme end into a straight beak-shaped point; whilst to both sides of the stumpy caudal extremity of the body short vesicular prominences are attached. The female reproductive outlet occurs at the commencement of the second half of the body. Thus, judging by its external characters this genus is most closely allied to Strongylus.” In reproducing Diesing’s description I have here rendered the translation somewhat more freely than in my previous record of the discovery given in ‘Nature’ (1871). The original description is supplemented by a brief account of the internal anatomy of the worm.

So far as I am aware no subsequent notice of this entozoon appeared until the year 1858, when Dr J. C. White gave some account of a “find” made in the United States. This re-discovery was reported in the sixth volume of the ‘Proceedings of the Boston Natural History Society.’ Dr White says:—“The worms were found in the leaf-yard of an apparently healthy hog, in the adipose tissue near the kidney. They occupied a space of the same about the size of a man’s fist and had burrowed through the mass in every direction, forming canals three or four millimètres in diameter, which terminated in cysts. On cutting open these cavities, which did not communicate with each other, they were found filled with pus, and in each were two worms, male and female.” Dr White expresses his opinion that the worms gained access to the tissues “by boring through the circulatory system while in the embryonic condition.” I think that Dr White deserves great credit for his correct diagnosis of the species, and all the more so because he was evidently not acquainted with Diesing’s original memoir. He expressly speaks of the “scanty descriptions” hitherto given of the worm. As Dr White had accurately determined the species in the presence of an American Scientific Society, it is remarkable that neither Verrill nor Fletcher should have identified the worm.

On the 10th of January, 1871, I received a letter from Prof. W. B. Fletcher, of Indianapolis, Indiana, U.S.A., and in it he announced that he had “found a worm” infesting the hog. The parasite was so abundant in swine that he obtained it in “nine out of ten hogs” which he had examined. Dr Fletcher sent me specimens of the worm for description and identification, when I at once recognised them as examples of Diesing’s Stephanurus dentatus. As Dr Fletcher’s first communication to myself was undated I do not know precisely when he first encountered the worm, but it was in 1870. In that same year Prof. Verrill received specimens of the worm. He says that they were received from Dr J. C. White. Failing to identify the parasites as Stephanuri, Verrill (making no allusion to the ‘Proceedings of the Boston Society’) not unnaturally supposed he had to deal with an entozoon that was new to science. Accordingly he immediately described and figured the worm under the combined title of Sclerostoma pinguicola. If these data are correctly given, the re-discovery of the worm in America was due to Dr J. C. White; its identity with Stephanurus being subsequently acknowledged by Diesing, and afterwards, quite independently, by myself. I gather this partly from Diesing’s ‘Kleine helminthologische Mittheilungen’ (s. 281), published as a supplement to his ‘Revision der Nematoden’ (1860–61). Until quite recently Diesing’s recognition of the identity of White’s parasites with Stephanuri was unknown in America. My conclusions arose from an examination of the actual specimens, whereas Diesing was entirely guided by White’s description. In this connection, moreover, a still more interesting re-discovery remained to be recorded. The original announcement which I made in the ‘British Medical Journal’ for January 14th, 1871, was followed by another in the same periodical for September, 1871. As stated in my second letter and repeated in my notice of Krabbe’s memoir on “Parasites” (‘London Medical Record,’ April 2, 1873), the President of the London Microscopical Society (through Mr Slack, who was at that time the secretary) forwarded to me a box of microscopic slides received by the Society from Australia. The slides displayed parasites of various kinds. Having been requested to identify the parasites I had the good fortune to recognise amongst them characteristic examples of Stephanurus dentatus. Thus was first made known the fact that this singular genus was not confined in its geographical distribution to the two American continents, but that it extended to Australia. The order of the principal “finds” and descriptions may therefore be thus restated. Natterer discovered the worm in Brazil in 1834. Diesing described it in 1839. Dr J. C. White re-discovered and identified the worm in 1858. It was subsequently found by Dr N. Cressy and by Dr Fletcher. These three observers all encountered the parasite in the United States (1858–70). Prof. Verrill re-described the worm as new to science in September, 1870. Diesing confirmed White’s diagnosis in 1860. I identified the worm from Fletcher’s “find” in 1871. Dr Morris supposed he had discovered a new entozoon in Australia in July, 1871. The Australian worms were identified by me as examples of Stephanurus dentatus in October, 1871.

The importance of Stephanurus in relation to porcine epizoöty and the supply of animal food cannot be ignored. As remarked in my communication to ‘Nature,’ it must be quite obvious that so large a parasite, when present in the hog in any considerable numbers, would give rise to serious disease, even if it were not productive of fatal results to the bearer. In one of his numerous communications to myself, Prof. W. B. Fletcher writes as follows:—“It is my opinion that this parasite is the cause, in some way, of the hog cholera, which has created such sad havoc within the past ten years over the pork-producing parts of America. One farmer told me, a few days ago, that within a month his loss alone from this cause was over one hundred head; and sometimes, in one neighbourhood, in a few days’ time, thousands have perished, although this season is not a cholera year, as our farmers say. I advised one farmer to burn or bury the dead animals, but he informed me that he believed that fewer hogs die of the disease after eating the dead animals than those kept from them. Unfortunately, in this State there is no law guarding the spread of disease, neither is there any reward of reputation or gain for pursuing any investigation that would bring pork and beef packers into disrepute. I myself could not get a pig’s kidney or beef’s liver in our city market, because I made investigations in some Texas cattle (being cut up in our market), which damaged their sale a few years ago.” In a third letter Dr Fletcher tells me that greater facilities for examining the carcases of hogs had since been accorded him through the liberality of a Liverpool firm of pork-packers, who had already killed 75,000 hogs during the summer season, i.e. up to the date of the first week in July. In hot weather the slaughtering is conducted in ice-houses. Prof. Fletcher’s views receive confirmation from the statements made by Dr Morris, who speaks of the pigs as dying from some mysterious disease, and thinks that the worms may be the cause of the porcine mortality. Writing to the President of the London Microscopical Society from Sydney (July 12th, 1871), Dr Morris says:—“It is just possible that some pigs may survive the irritation such a swarm of young worms must set up; others, again, may die from peritonitis, hence the sudden deaths amongst the pigs.” I think Dr Morris’ view is perfectly correct, but whether it be so or not, it is (as observed by me in ‘Nature’) interesting to notice the remarkable correspondency of the conclusions arrived at by Drs Fletcher and Morris independently. It will probably not be difficult to ascertain hereafter whether or not the maladies respectively termed “hog cholera” and “mysterious disease” are one and the same disorder, but whatever happens in this respect, it is now quite clear that this parasite, hitherto little regarded, and for many years past persistently overlooked, is extraordinarily prevalent in the United States, and, perhaps, equally so in Australia; it being further evident that its presence in the flesh of swine is capable of producing both disease and death. The statement of the worthy American farmer that the swallowing of infested flesh by pigs does not necessarily involve the pig-eating hog in a bad attack of the so-called “cholera disease” requires to be further tested, and it also remains to be proven whether or not the Stephanurus be capable of passing through all its developmental changes from the egg to the adult form within the body of the bearer without having at some time or other gained access to the outer world. The comparatively large size of the ova, which I find to be about 1/105″, or more than four times the size of Trichina-eggs, is not without significance, but as yet we are entirely unacquainted with the larvæ of Stephanurus. If no intermediary bearers are necessary to its development, we ought not to have to wait long for a complete record of the life-history of Stephanurus dentatus. In conclusion, I will only further remark that since thousands of hogs are infested by this entozoon the subject is worth further investigation. I believe that Prof. Fletcher brought the matter under the notice of the United States National Swine Breeder’s Association, which met at Indianapolis in November, 1872, but with what success I have been unable to learn. The wealthy agricultural societies of Great Britain pay little or no regard to the subject of parasites, although thousands of valuable animals annually perish from the injurious action of entozoa.

Of the remaining nematodes infesting swine I must particularly mention Sclerostoma (Strongylus) dentatum and Strongylus paradoxus, the last named being generally regarded as identical with Dujardin’s S. elongatus. The first of these two parasites infests the small intestines, the male and female worms alike measuring about 1/2″ in length. The females are sometimes a trifle longer. The Sclerostoma dentatum is an abundant parasite, infesting all varieties of swine and also peccaries; but it is apparently incapable of serious injury to the bearer. Schneider selected the male S. dentatum for classificatory purposes. In this worm the arrangement of the rays of the hood is simple, forming a good central type. Dr D. V. Dean, in his excellent report of St Louis Board of Health (1874), speaks of Strongylus dentatus as if it were the same entozoon as Stephanurus. The confusion of nomenclature would have been avoided if Diesing had called the renal worm Stephanurus Nattereri. I hope this title will yet be adopted to prevent future mistakes. The lung-worm (S. paradoxus) is by no means harmless, being a frequent cause of fatal husk in young pigs. It is a viviparous worm, the females acquiring a length of 11/2″, whilst the males rarely exceed 3/4″. Under the title Gongylonema pulchrum, Molin has noticed yet another filariform nematode infesting the wild hog; and, lastly, the lamented Russian traveller, Fedschenko, has published a full description of a new species of Gnathostoma (G. hispidum), which infests the coats of the stomach alike of the wild and domestic hog. One of the most interesting parasites of swine is the large acanthocephalous entozoon (Echinorhynchus gigas). It infests the small intestines both of the wild and domesticated hog, and it was also obtained by Natterer from the collared peccary of Tayazou. Common as the great Echinorhynchus is in the United States (and it is scarcely less so on the Continent) I believe that few, if any, of the museums in the United Kingdom of Great Britain contain this large entozoon. It is a curious fact that it does not exist in the Hunterian Collection, where, however, there is displayed a very fine set of acanthocephalous parasites from whales. When in the year 1865 I mounted, with my own hands, 200 preparations of entozoa for the Museum of the Royal College of Surgeons, I had not so much as seen a specimen of this worm. Much scientific interest attaches to this parasite from the fact that Schneider discovered that the embryos of E. gigas take up their residence in the larvæ of the cockchafer (Melolontha vulgaris). He thinks it identical with the Echinorhynchus hominis of Lambl. Leuckart disputes this identity, and compares Lambl’s worm with the Echinorhynchus angustatus of our fresh-water fishes. The E. spirula of certain Brazilian monkeys and of the Barbary ape bears a strong resemblance to the species from the hog. On the strength of Lambl’s case—and it is the only genuine instance of the kind on record—Prof. Leuckart devotes no less than 125 pages of his great work to the consideration of the structure and development of the thorn-headed intestinal worms. This worm demands especial attention. Speaking of the hog’s Echinorhynchus, Prof. Verrill, in his ‘Connecticut Report,’ says that “sometimes the intestine of a hog is found perforated by so many holes that it cannot be used in the manufacture of sausages.” From Mr George Wilkins I learn that the pig-slaughterers of our English metropolis are well acquainted with these perforations, which are sometimes so numerous that the gut looks as if it had been “riddled” with swan-shot. No wonder that diseased hogs, afflicted with these formidable parasites, go about, as Verrill expresses it, “continually squealing and grunting, especially in the morning.” That they are also “cross and morose, and given to biting and snarling at their companions,” is by no means astonishing. “In severe cases,” remarks Verrill, “hogs afflicted with this parasite are weak in the loins, and have the membranes in the corners of the eyes swollen, watery, and lighter colored than usual.” It is some comfort to know that Lambl’s human case is unique, and that so long as people abstain from eating cockchafer larvæ they are not likely to be infested by Echinorhynchus gigas. In the first book of this work I have given my reasons for not regarding Welch’s “encysted Echinorhynchus in man” as a genuine example of this curious genus of entozoa.

The external parasites of swine are not so numerous as might be expected from the habits of their hosts. The most common ectozoon is the hog louse (Hæmatopinus suis). This disgusting little insect is about 1/8″ in length. Almost equally common is the hog mite. Though hitherto considered as a distinct species (Sarcoptes suis, Gurlt), it is regarded by Mégnin as a mere variety of Sarcoptes scabiei. As Gerlach and others have remarked, it is readily transmissible to man. The Sarcoptes squammiferus, of Fürstenburg, is only another name for this variety of S. scabiei. Speaking of this scab-insect Mégnin says:—“This parasite was first encountered by Spinola and Gurlt, and afterwards by Müller.” He then adds:—“A Ceylon wild boar died at the menagerie of the Museum of Paris of a chronic affection of the skin which had transformed its integument into a vast lichen.” Lastly, as regards the protozoal parasites I can only remark that the psorosperms (spoken of as Rainey’s corpuscles or as Miescher’s utricles) are often very abundant in the flesh of otherwise perfectly healthy swine. Having dwelt upon the character of such organisms in the first moiety of this work, I will only remark that the full significance of these singular bodies yet remains to be determined. Rainey’s notion that they represented early stages of cysticercal growth is altogether untenable. According to Behrens, as quoted by Davaine, psorosperms are especially abundant in the flesh of swine which have recovered from the disease called mal rouge. On the subject generally, the writings of Rivolta, Waldenburg, Eimer, and Siedamagrotsky are especially trustworthy. Full references to these and other authorities are given in the synopsis of the 2nd edition of Davaine’s well-known treatise.

Bibliography (No. 54).—(Anonymous), “On Parasitic Maladies, especially Measles, of the Pig,” from ‘Scottish Farmer and Horticulturist,’ in ‘Edin. Vet. Rev.,’ p. 688, 1861.—Ballard, E., “On Diseased Meat, and what to observe in cases of suspected Poisoning by Meat or Sausages (infected with Entozoa, &c.),” ‘Med. Times and Gaz.,’ Jan., 1864.—Bowditch, H. J., “Raw Pork as an Aliment (without reference to the question of Entozoa.—T. S. C.),” ‘Boston Med. and Surg. Journ.,’ vol. lv, 1857; see also ‘Comments,’ vol. lvi, pp. 23 and 69, 1857.—Cobbold, “On the Discovery of Stephanurus in the United States and in Australia,” in ‘Nature,’ Oct. 21, 1871, p. 508, and in ‘Brit. Med. Journ.,’ Jan. and Sept., 1871; also in the ‘Monthly Micros. Journ.,’ Nov., 1871.—Idem, “Internal Parasites of the Hog,” in ‘Manual,’ chap. xii.—Idem, “On Cystic Entozoa from the Wart-Hog and Red River Hog,” ‘Proc. Zool. Soc.,’ 1861.—Idem, “On Simondsia,” ‘Entoz.,’ p. 79.—Idem, “Note on Worms in the Lungs of a Pig,” in the ‘Field’ for Jan. 9, 1864.—Idem (in relation to Cysticerci or Measles, see Bibl. Nos. 13 and 14, and, for remarks on psorosperms, Bibl. No. 41).—Cressy, N., ‘On the Diseases of Domestic Animals in Connecticut (2nd and 3rd Ann. Reports),’ Hartford, U.S., 1873–74.—Idem, “The demands of Agriculture on Veterinary Science,” in ‘Rep. of the Mass. Board of Agric.,’ 1874.—Idem, ‘Find of Sclerostoma’ (quoted by Verrill).—Crisp, “Note on Hydatid Cysts in the Abdominal Cavity of various Hogs,” ‘Path. Soc. Trans.,’ 1863.—Dardel (see Bibl. No. 14).—Davaine, “Ladrarie chez le porc,” in his ‘Traité,’ 2ème edit., p. 668 (see also the writings of Delpech, Guardia, and especially Reynal, quoted at p. 674).—Dean, D. V., “On Meats and Parasites,” in ‘Seventh Ann. Rep. of Board of Health of the City of St Louis,’ 1874, p. 58 et seq.—Diesing, ‘On Stephanurus’ (quoted in text above).—Dupuy, “Hydatid in a Pig,” from ‘Journ. Théorique et Prat.,’ in the ‘Veterinarian,’ vol. iv, 1831, p. 285.—Fedschenko, ‘Description of new Species of Tetrastemma, Prorhynchus, and Gnathostoma’ (in the Russian language), Moscow, 1872.—Fleming, A., “Measly Pork as Food for Man,” ‘Edin. Vet. Rev.,’ vol. i, p. 485, 1858–59.—Idem, “On the Measle of the Pig, and on the Wholesomeness, as Food for Man, of Measly Pork,” ‘Dubl. Quart. Journ.,’ 1857.—Fletcher (quoted in text above).—Florman (quoted by Rudolphi, ‘Synops.,’ p. 620, 1819; and by Davaine, l. c., p. 723, 1878), in ‘Vetensk. Acad. Nya Handlingar,’ 1810, pp. 179–182.—Gairdner, W. T., “Case of Tapeworm occurring in connection with the Eating of Raw Pork,” ‘Edin. Month. Journ.,’ 1856, and in the ‘Veterinarian,’ vol. xxix, p. 228, 1856.—Gamgee, J., “On Diseased Meat,” ‘Pop. Science Rev.,’ Jan., 1861.—Gordon, “On Tapeworm from Unwholesome Food,” ‘Med. Gaz.,’ 1857.—Gross, S. D., “Note on the frequency of Acephalocysts in Swine at Cincinnati,” in his ‘Elements of Path. Anat.,’ p. 118, 1845.—Gurlt, E. F., ‘Lehrbuch der path. Anat. der Haus-Saügethiere,’ 1831, s. 46, 51, 142, 385.—Heller (see Bibl. No. 13).—Krabbe, ‘Husdyrenes Indvoldsorme’ (l. c., in text; see also review in ‘Lond. Med. Rec.,’ April 2, 1872, p. 206).—Leidy, “Note on Trichina spiralis from the Pig,” from ‘Rep. Acad. Philad.,’ in ‘Ann. Nat. Hist.,’ vol. xix, 1847.—Leuckart (see Bibl. No. 13).—Lewis (Bibl. No. 13).—Martin, J., “Case of Hydatids in the Liver of a Sow,” ‘Trans. Vet. Assoc.,’ pp. 330 and 364, 1842–43.—Mégnin (Bibl. No. 14).—Molin, ‘Una Monog. del Gen. Spiroptera,’ Wien, 1860.—Morris, “Report on Australian Parasites,” ‘Month. Microsc. Journ.,’ Nov., 1871.—Percy, S. R., “On Diseased Meat in relation to Public Health (Prize Essay),” ‘New York Med. Journ.,’ 1866.—Idem, “On the Food of Cities (an Address),” ‘New York,’ 1864.—Perroncito (Bibl. No. 13).—Putz (Bibl. No. 14).—Rainey (Bibl. No. 14).—Rigetti (Bibl. No. 14).—Sawer, A., “Trichina,” in ‘Bost. Med. and Surg. Journ.,’ 1865, p. 16.—Schmidt, Max (see Bibl. No. 51).—Tartivel (Bibl. No. 14).—Thudichum (Bibl. No. 13).—Tommasi (Bibl. No. 13).—Verrill, “On Sclerostoma,” ‘Amer. Journ. Sci. and Arts,’ Sept., 1870.—Idem, “The External and Internal Parasites of Man and Domestic Animals,” from ‘Rep. of the Conn. Board of Agriculture,’ 1870, p. 109.—Walker (see Bibl. No. 20, o).—Wheeler, E. G., “Worms in the Lungs of Swine,” ‘Bost. Med. and Surg. Journ.,’ 1841.—White, J. C., “On Stephanurus,” ‘Proc. Bost. Nat. Hist. Soc.,’ vol. vi, p. 428, 1858.

Part XI (Cetacea).

The parasites of whales are excessively numerous. Unfortunately only a few of the species have been carefully studied, and much confusion necessarily exists as to the number of distinct forms. This statement is especially applicable to the entozoal group, which comprises upwards of a score of species. Probably Van Beneden has examined more of these parasites than any one else, and what little is known respecting them is for the most part due to his investigations. I have myself encountered and described several new species—a circumstance which Prof. Van Beneden appears to have altogether overlooked.

Commencing with the flukes, the first species I notice is Distoma lancea. The late C. M. Diesing’s description of this worm was based upon specimens obtained by Natterer in Brazil. The worms were discovered in the biliary ducts of a male dolphin dissected at Barra do Rio Negro on 29th December, 1833. Natterer calls this cetacean the tacuschi, and in a letter to Diesing names the species Delphinus tacuschi, in order to distinguish it from the D. amazonicus of Spix and Martius. Prof. Flower has shown that Spix and Martius’s D. amazonicus is referable to the inia or Bolivian dolphin (Inia Geoffroyi). The views of Flower, Natterer, and Diesing are thus far in agreement; and the geographical position of Barra shows that Natterer’s dolphin could not be the inia, since, as Blyth long ago remarked, this last named cetacean “inhabits only the remote tributaries of the Amazon and the elevated lakes of Peru.” Several other dolphins from Brazil have been described, one of which Mr Gray named Steno tacuxi. I think that Gray’s cetacean answers to the Delphinus tacuschi of Natterer; but Prof. Flower is of opinion that Gray’s species is an ordinary Delphinus. In this case it may, he thinks, probably be referred either to the D. fluviatilis or to D. pallidus. Whichever view is correct, it is clear that Natterer’s parasite was obtained from a fluviatile cetacean, and not from an oceanic or even an estuary form. In Diesing’s original description it is stated that Natterer found the Distoma lancea “once only,” when numerous examples were secured. To Dr Anderson I stand indebted for a solitary specimen, which he procured from the short-snouted dolphin (Orcella brevirostris, Owen). The obliging superintendent of the Calcutta Museum obtained this Distoma on the 3rd of January, 1873. He removed it from the duodenum, but it had probably escaped from the liver. Be that as it may, I easily recognised the species by the sinuosities of the margin of the body. Dr Anderson’s parasite does not exhibit these marginal irregularities so distinctly and sharply as they are shown in Diesing’s figures. Diesing remarks that the internal organs may be seen through the transparent body. The uterine organs, crowded with ova and of a purple color, are represented by him as branched after the fashion of a raceme. The artist has been misled. The uterine channel is not branched. Dr Anderson’s specimen showed two large oval testes placed one above the other in the middle line, and rather higher up than is usual with those distomes that have the organs presenting this simple form. The ducts were not visible. The yelk-forming glands were particularly well marked, consisting of two laterally-disposed masses, the left gland extending higher up than its fellow. The so-called yelk-cells or capsules were well seen. The oval-shaped eggs were tolerably distinct, yielding a length of 1/750″ from pole to pole, by about 1/900 in transverse diameter. The worm, when unrolled, did not exceed 1/6″ at most, whereas some of Natterer’s specimens measured 1/2″ in length. The neck had lost that rounded character which Diesing called skittle-shaped (kegelförmige). The ventral acetabulum is very nearly twice as large as the oral sucker. Diesing represents the ventral sucker as circular; but in Anderson’s specimen this organ was broadly oval.

The next fluke I have to notice (Distoma Campula) is better known to me. In the twenty-second volume of the ‘Linnean Society’s Transactions’ I first described this new fluke, having secured numerous examples from the peripheral branches of the biliary ducts of a porpoise (Phocæna communis). The apparently healthy cetacean was shot by Mr Jardine Murray in the Firth of Forth, in April, 1855. I mention its condition because the bile-ducts were found to be diseased in a way similar to that ordinarily observed in cases of fluke-rot affecting sheep, cattle, and other animals. In my MS. note-book I remarked: “The liver-ducts were in several places thickened and knotted near the surface of the organ. On opening these they were found to be loaded with small distomata.” It was added that, so long as the flukes were alive, they displayed under the microscope a “double and peculiar intestinal tube,” the skin being clothed with spines arranged throughout with perfect regularity. When the superficial ducts were dissected out they presented a distinctly beaded appearance, the enlargements of the lumen being occupied by flukes closely packed together. At least twenty were found in one spot. One of these enlarged ducts is figured in my recent paper to the Linnean Society (quoted below). The most striking feature connected with the structure of Distoma Campula is the twisted condition of the digestive canals. They present a zigzag appearance, the lateral folds being so sharp that they seem to constitute, as it were, a transition between the ordinary simple intestinal tubes of a true Distoma and the branched tubes seen in Fasciola. This led me originally to place the worms in a distinct genus (Campula). Perhaps there were no sufficient grounds for this generic separation; but in all Dr Anderson’s specimens obtained from the liver-ducts of the Gangetic dolphin more or less decomposition of the contents of the intestinal tubes had occurred, consequently the angular appearance of the folds is entirely lost. From the other characters presented by the worms I believe that these flukes from the Ganges are specifically identical with those originally obtained from the porpoise of the Firth of Forth. For reasons elsewhere stated at full length I have merged my genus Campula into that of Distoma. Thus, Campula oblonga is a synonym only. I cannot here treat of the morphology of trematode organisation as it deserves; but in relation to the question of transition-forms I may remark in passing that an extreme degree of intestinal folding seems as if it must result in branching. This, I think, would happen should any departure from the central distome type be rendered necessary by the exigences of the creature. At all events, the spirally-twisted and branched digestive organs constitute different ways in which nature attains one and the same end. I may add that this coiled condition of the tubes in D. Campula is by no means unique, since I have seen it in other trematode forms, as, for example, in my D. compactum from the Indian ichneumon. Dr Anderson’s specimens of D. Campula furnish a good general view of the reproductive organs. They show that the single, relatively narrow, and unbranched uterine canal is of great length, and coiled upon itself in a very tortuous manner. In this way the duct passes from side to side, crossing the central line of the body at least a dozen times, whilst every fold is likewise bent upon itself to such an extent as to increase its length to at least four times that of the animal. In short, the uterine folds may be described as passing from side to side, each separate coil being twisted upon itself so as to form secondary coils. In the fluke here drawn I have accurately represented every winding of the duct, from its vaginal outlet above to its termination, where it is joined by the ovarian and vitelligene ducts in the ordinary way. Only the merest traces of these smaller channels were visible; but the two oval testes were well defined, occupying a position somewhat lower down than usual. There was a third organ, apparently the ovary. This was less well defined, and situated higher up in the middle line. The vitelligene glands occupied the usual position. The terminal cells or capsules with their efferent ducts were well seen in several specimens. The water-vascular system was constantly visible, or at least that part of the main channel which expands into a large vesicle immediately above the central point of the tail. At this part several of the specimens ruptured. In all of the worms the lower end exhibited a sort of tail, resulting from post-mortem changes. None of the Edinburgh specimens of Campula displayed either the slightest trace of this projection or of the water-vessel connected with it. The uterine duct was filled with eggs. Approximately, the ova gave a measurement of 1/1000″ from pole to pole by 1/2100″ in breadth. Although in Anderson’s specimens the integumentary spines had fallen off, they are still attached in my original specimens from Edinburgh. The spines average 1/500″ in length. With their shafts directed downwards they separately presented the form of a long cone, the base of which was only 1/1000″ broad. After describing the above-mentioned trematodes I received a letter from Dr Anderson, in which he enclosed a sketch of a parasite taken from the small intestine of another Platanista. The illustration evidently represented a new species of cetacean fluke which I called Distoma Andersoni, with the following diagnosis:—“Body oblong, smooth externally, uniform in thickness, six times as long as broad; head with lateral projections; ventral sucker large and prominent; neck much constricted; tail evenly rounded off, blunt. Length 1/8″, breadth about 1/50″.” This worm, which was discovered by Anderson, in March, 1873, is figured in my memoir communicated to the Linnean Society. Only one parasite was found. The figure in question shows that in this species the testes are globular and placed high up in the middle line of the body. A small lobed gland immediately above the testes is probably the ovary. The vitelligene glands are largely developed. In the year 1858 Van Beneden described a large fluke from the pike-whale (Balænoptera rostrata). The specimens were from Eschricht’s collection and had been removed from the liver. As some of the examples measured no less than 80 millimètres, Van Beneden described them as “the largest known distomes.” This is probably correct, but the great human fluke (D. crassum) reaches 21/2″, and the giraffe’s fluke (Fasciola gigantea) 3 inches in length. The curator of the Australian Museum, at Sydney, Mr Gerard Krefft, mentions a Distoma which himself and Mr George Masters obtained from Delphinus Forsteri. Not improbably it represents a new species. Of the single-suckered flukes, Creplin in 1825 obtained Monostoma plicatum from the intestines and œsophagus of a northern whale. This cetacean was obtained on the coast of the island of Rugen, in the Baltic. It has been variously spoken of as Balæna borealis or B. rostrata, but by Van Beneden this cetacean is called Balænoptera musculus. The flukes exceeded 1/4″ in length. Another species of monostome (M. delphini) was vaguely indicated by Blainville as occupying the cutaneous follicles of Delphinus Dalei, which cetacean is a synonym of Micropteron sowerbiensis. The same worm is supposed by Van Beneden to infest the bottle-head (Hyperoodon butzkopf), and perhaps it was the same or a similar worm which Poelman found in the flesh of Lagenorhynchus Eschrichti. By naturalists imperfectly acquainted with helminths, the monostomes are apt to be confounded with Cysticerci; nevertheless, these widely different types may coexist in the same host. The presence of larval cestodes has been indicated in various whales. Thus, F. Cuvier and Van Beneden state that Surgeon-Major Carnot, in 1822, found an enormous quantity of small hydatids in the nasal sinuses of a porpoise (Phocæna compressicaudata). These are supposed to be Cysticerci. In like manner Mr F. D. Bennett, in 1837, obtained numerous capsuled Cysticerci from the skin and blubber of Catodon (Physeter) macrocephalus. It is unfortunate that so few of the cetacean helminths find their way into the hands of persons competent to decide upon their true character.