At 3 p.m. I intended to have examined one or more of the earth-worms placed in the open-mouthed phial, but all had escaped and buried themselves in the fern-mould out of reach.
At noon on the 30th I renewed my examination of the two large larvæ whose developmental changes I had been instrumental in producing from the time of their escape from the egg-coverings. I saw no reason to doubt that the sequence of changes thus far noticed referred to the species of parasite under consideration. Both larvæ were active, but the moulting one had now completed its ecdysis. Its sexual distinctiveness had become yet more pronounced by the formation of two rather short and stout spicules, the point of the tail displaying a very minute awl-shaped projection. The lateral membranes had not visibly increased in size. One of these larvæ, the first under observation, now perished from the injuries sustained during inspection.
Again, and later in the day, I sought to clear up any doubts that might still suggest themselves respecting the source of these larvæ, by once more submitting the intestinal contents of two fresh and uninfected earth-worms to careful scrutiny. In the first worm no parasite could be found, and in the second only one minute nematoid; its organisation, which was sexually incomplete, neither corresponded with my strongyle embryos, nor, so far as I could judge, with Goeze’s Ascaris minutissima microscopica (the Anguillula lumbrici of Diesing and others), nor with Dujardin’s Dicelis filaria. It was a very long and narrow creature, but I lost it whilst attempting to secure an accurate measurement. I should say it was about 150th of an inch in length, and not more than 11500th in breadth. I made a rough outline sketch of it.
In view of further observations I now placed five more earth-worms in the jar containing strongyle embryos, and I also placed six others in the phial which contained coarser mould, and only a comparatively small number of the original strongyle embryos. The phial was closed with a cork and half buried in the fern-mould of one of my larger Wardian fern-pans. Before this transfer was made I again took an opportunity of ascertaining by microscopic evidence that the embryos lodged in the coarse and fine mould had none of them made the slightest advance in organisation. The worms placed in the jar immediately proceeded to bury themselves.
At noon on the 1st of November I sought to get further results from the only large free larva which now remained to me (for the fern-pinnules on which the larvæ were originally placed had dried up and no third specimen could be discovered). Structurally the larva presented no advance. It therefore appeared to me necessary to place it under new conditions in view of exciting further progress towards sexual maturity and adult growth. To transfer it to the bronchus of a living calf would, of course, have been the crucial experiment, but the hopelessness of getting any satisfactory result from this solitary transfer deterred me from the attempt. On a larger scale, with many larvæ, a positive issue would of course prove decisive. Accordingly, the only thing I could do, in partial imitation of nature, was to try and induce some further changes by placing the larva in human saliva, kept warm artificially. As a first step I immersed the creature in a little of the secretion added to the glass slide, when it immediately displayed very lively movements, such as could only be fitly described as frantic. This encouraged me to replace the slide under one of the fern shades without applying any additional heat. I then left it.
At 12.30 p.m. I selected three of the eleven worms lodged in the infested earth, namely, two from the jar and one from the closed phial, and made a microscopic examination of their respective intestinal contents. In one of the worms from the jar I found several embryos clearly referable to my strongyles, their structure showing scarcely any advance upon that exhibited by the embryos in the mould itself. The weather was now excessively cold and the larvæ were motionless; nevertheless, the application of warmth showed that they were by no means dead. The fæcal matter obtained from the worm that had lived in the phial displayed an immense number of infusoriæ (Bacteria) which rushed about rapidly over the field of the microscope. No other signs of life were detected.
On the 2nd of November I found my solitary strongyle larva alive, but its movements, though active, were by no means so active as on the previous day. No fresh structural changes had occurred.
At noon on the 3rd the larva at first lay almost motionless in the now thick and ropy saliva; nevertheless, on applying a thin glass cover its movements became tolerably vigorous. During its quiescent state I succeeded in getting a good view of the caudal rays and other imperfectly developed organs, of which I retain figures.
Having now satisfied myself that other new conditions were necessary to enable the larva to arrive at sexual maturity, I sought to transfer it to a glass tube filled with fresh saliva. This transfer was a matter of difficulty. After passing the thick ropy saliva into the tube, I examined the slide and found that the larva was gone. I concluded it was in the tube, which, in order to keep the contents warm, I subsequently carried about concealed in my under-clothing during the day and placed in my bed during the night. This increase of temperature, however, caused decomposition of the saliva; so when next day I diligently sought for my experimental nematode it was nowhere to be found. Thus terminated my observations on the first set of embryos, which had enjoyed their temporary sojourn in the intestinal tract of the earth-worm, and which had certainly afterwards undergone a series of marked structural and morphological changes, accompanied with ecdysis.
The weather had now been for several days exceedingly cold, but on the 4th a favorable change set in, which led me to hope that I might be able to verify the facts above recorded. Accordingly, as a new point of departure, I re-examined the fine mould, and at once found my embryos in a high state of activity. The mould, however, appearing too moist for the earth-worms, I permitted further evaporation before closing the jar with a glass cover. Four days subsequently I examined the intestinal contents of two of the earth-worms. In one of these, an inch in length, no parasite of any kind could be detected; but in the other, which was beyond three inches in length, there were numerous Opalinæ besides several strongyle embryos, the latter presenting characters not visibly in advance of those still living in the mould. All of them were motionless, as if they had not got over the shock produced by previous cold. Moreover, the weather had again become cold, and thus, when I again inspected my experimental embryos living in the jar, I also found them motionless, so different from their behaviour on the 4th. However, since a further result with the earth-worm embryos appeared possible, I placed some of the fæcal matter, already ascertained to contain a few of them, on the fronds of a thoroughly moist and dew-covered Asplenium bulbiferum. This plant was in a fern-pan which had the advantage of considerable fire-warmth during the day. When, however, on the 15th of November, I examined the fæcal earth removed from several of the pinnules, I failed to find any of the embryos. Possibly they had wandered, for the entire frond was covered with dew-drops, which was not the case with the fern that I had previously experimented on with such satisfactory results. At all events, whether they had wandered or had perished, their apparent absence in no way affects my previous record; and the more so since only a few had been observed in the fæcal matter. The smallness of the number found in the earth-worm was also readily accounted for. Thus, when at 1.30 p.m. on the 15th I made a diligent search for embryos in several grains of the fine mould, not a single young strongyle could be detected. Possibly the frost of the previous night had killed them. The earth-worms were still alive and in good condition.
In conclusion, I may observe that every experimenter with helminths is well aware how unfavorable the winter season is for this kind of research. If a repetition of this inquiry in the spring or summer should confirm these results, it will prove a clear and substantial addition to our knowledge of the development of the strongyles. Meanwhile, I think that the data above given render it highly probable that the larvæ of the hoose-producing strongyle (S. micrurus) are passively transferred to the bodies of setigerous annelids, which are thus called upon to act as intermediate hosts. If this be so, it is further certain that important structural changes with ecdysis follow after their escape from the earth-worms or other annelids, moisture, dew, or water being essential to the penultimate stage of growth. Final passive transference, either with fresh fodder from swampy grounds, or, it may be, from pond water, ultimately enables them to acquire their definite sexual form, size, and other adult characteristics.
According to Mégnin it is not the Strongylus filaria, but a hitherto unknown and totally distinct species (Strongylus minutissimus) which occasions pneumonia in Algerian sheep. In England the parasitic bronchitis affecting sheep is generally called the “lamb disease.” This is unfortunate, because many other parasites prove destructive to lambs. One of the most injurious species is Strongylus contortus, infesting the true stomach, whilst S. hypostomus, occupying the small intestines, is almost equally obnoxious to the ovine bearer. By Leuckart and others this last-named worm is retained in Dujardin’s genus Dochmius, in which genus another species occurs (D. cernuus). This worm is quite distinct, but not readily distinguishable by the naked eye alone. It occasionally occupies the upper part of the colon, as well as the lower end of the small intestine. A rarer intestinal worm in lambs is the Strongylus filicollis. Several other strongyles infest the ox (S. radiatus, S. inflatus, S. gigas), goat (S. venulosus), and stag (S. ventricosus).
As showing the extraordinary prevalence and destructiveness of entozoa in certain countries, I will adduce an instance in which my opinion was requested and given some five years since. My informant stated the case somewhat in the following manner:—On a farm in New South Wales, and lying about 200 miles to the north-west of Sydney, on the Trafalgar tributary of the Macquarie river, out of a flock of about 8000 sheep no less than 1200 have perished. In many instances post-mortem examinations were made, worms appearing in all cases to be the cause of death. There were four kinds of parasites present. The most numerous were red and white, “marked like a barber’s pole.” These occurred chiefly in the fourth stomach and commencement of the duodenum, but some were found throughout the entire length of the small intestine. A second set comprised small black worms, resembling needles, scattered only in the lumen of the intestines. The third set were tapeworms, each being several fathoms in length. The fourth set was made up of white threadworms, individually measuring two inches in length. These occupied the bronchial tubes, and were characterised by my informant as “the most deadly of all.” Without the aid of specimens I at once recognised these brief diagnostic characters as severally referring to Strongylus contortus, Dochmius hypostomus, Tænia expansa, and Strongylus filaria.
What the inquirer desired at my hands was “full information respecting the general principles to be carried out in view of the prevention of this parasitic disease, regard being had to the difficulty of finding any food but pasture, to the number of animals to be treated, and to the not unfavorable circumstance that the run is divided by fencing to a great extent.” I was also requested to explain the best modes of treatment, being at the same time informed that turpentine drenchings had already been employed with only “partially effective” results. I was also expected to give numerous and varied formulæ, to be tried in succession, supposing the first should fail. Of course, it should have been known that I neither prescribe medicines nor accept fees in respect of animal patients; but, as in this instance my opinion was permitted to assume the form of a “written scientific report,” I was pleased to have an opportunity of commenting freely and fully on the significance of the facts submitted. My advice took the form of a long report, which might here be usefully given in extenso were it not somewhat of the nature of a private and privileged communication. I have no doubt that the stockowner would be pleased that I should utilise his remarkable “case” for the benefit of agriculturists and others; but it is for him to publish the “opinion” as it stands, should he think fit to do so.
Practical men, on reading the few foregoing particulars, will perceive that one of the principal obstacles to success in cases of this kind lies in the circumstance that artificial food can only be procured with difficulty. Where the source of the disease is associated with the pasture-supply, any treatment, however effectual for a time, can only be followed by partially satisfactory results.
The destructive powers of any one of the above-mentioned parasites being sufficient to produce a fatal lamb-disease, it is clear that when two or more of these particular species attack their victim in considerable numbers, the ovine-bearer has little chance of recovery. The intestinal strongyles, by means of their oral armature, behaving as veritable leeches, will, if not expelled in good time, produce a rapidly fatal anæmia, precisely in the same way as the human Anchylostomum of the tropics.
The worst of dealing with this sheep-parasite is that it will not succumb to ordinary doses of salines like the stomach strongyle; moreover, the little leech-like wounds will probably bleed after the parasites have been compelled to abandon their hold. Prevention is better than cure. Accordingly, I sought to explain the origin of these creatures, and in what possible ways the germs of the various species could be destroyed, or at least limited in numbers.
As to the drugs and inhalations to be employed, it would be difficult to advise any more effective than those commonly in vogue, the great thing being to effect changes of pasture and ground, to look to the purity of the water-supply, and to supply the best kinds of nourishment after active treatment. The diseased animals should, from the very first, be separated from their companions, because the amount of germ distribution is thereby greatly lessened. They should be at once drenched or treated by inhalation (as the parasitic nature of the attack requires), and the enclosure in which the animals have been temporarily housed should be thoroughly scoured with boiling-hot water impregnated with salt.
The nomenclature of the parasitic diseases of animals is excessively vague. Thus, apropos to the case above recorded, I may mention that an American veterinary practitioner appeared to be much shocked that I should have had the temerity to speak of four distinct kinds of lamb-disease. It is in this way that practical men often commit serious mistakes by rolling together disorders that are totally distinct. If it were true that epizoöty in lambs is exclusively due to Strongylus filaria, then professionals might aptly speak of the parasitic bronchitis of young sheep as lamb-disease; but we now know that several other helminths prove terribly fatal to lambs, occasioning death in totally different ways. In one set of cases the animals are asphyxiated; in another set they become fatally anæmic; and in a third set they perish from the severity of nervous reflex irritations. Lastly, it may be remarked that, in view of the successful management of the parasitic disorders of animals, the veterinary practitioner must necessarily be guided by the same general principles as the physician. For myself, I may say that I have hitherto designedly withheld many practical hints which a long experience with human patients suggested, not wishing to appear to dictate to those who are constantly seeing animals. However, since (contrary to my own wishes) it has happened that both professional men and agriculturists have not only invited me to give opinions, but have, at various times, asked me to prescribe, it seems there can have been no impropriety in publishing my views on this subject. Certainly I have had no professional motives to serve.
Of the few non-strongyloid nematodes, one of the commonest is Trichocephalus affinis. I have obtained this worm from the giraffe, and the parasite may be said to infest all ruminating animals, not excluding even the camels and llamas. As before remarked, the whipworm has been known to produce severe symptoms in man, and it occasions “scour” in the sheep. The eyes of cattle are occasionally infested by Filaria lacrymalis and F. papillosa. The last named is the common eye-worm of the horse. On Feb. 27th, 1875, Dr Edward L. Moss, of H.M.S. “Alert,” brought me three examples of a nematode which I referred to Filaria terebra. Dr Moss obtained these parasites in 1874, during the time that he had charge of the Naval Hospital at Esquimalt, Vancouver’s Island. They occupied the abdominal cavity of the black-tailed deer (Cervus columbianus). The worms were mostly found lying amongst the coils of the small intestine. They were not attached to the peritoneal membrane. Dr Moss had shot seventeen deer in all, the males and females being in about equal proportion; nevertheless, not one of the bucks showed any trace of the presence of these entozoa. This absence of parasites in the male deer is noteworthy. Hitherto the worm appears to have been observed in the red deer (C. elaphus), and by Natterer in three species of American roe (C. rufus, C. simplicicornis, and C. nambi). Two of the worms measured each about 213″ in length, the third exceeding 3″. They displayed in profile two prominent oral papillæ. Probably there were four of these processes, such as Dujardin described in his Filaria cervina, which, according to Diesing, is a synonym. They all possessed spirally twisted tails.
Amongst the arachnidan parasites of ruminants having entozoal habits are Pentastoma denticulatum and P. constrictum. The former larval worm is excessively common in cattle, sheep, deer, and antelopes. According to Rhind, the adult worm (P. tænioides) also infests the sheep. The P. constrictum has hitherto only been found in the giraffe. On the 10th February, 1859, I obtained numerous examples (P. denticulatum) from a bubale (Antilope bubalis) which died at the Zoological Society’s Gardens. The greater number occupied the surface of the lungs and intestines; some few, however, were enclosed in cysts beneath the pleura. In the spring of 1860 I also procured several specimens from the abdomen of a cape guevi (Cephalopus pygmæus).
The ectozoa of ruminants have received much attention, but I can merely indicate the known forms. Following Mégnin’s classification we have three well-marked varieties of the acarine genus Sarcoptes (S. scabiei, var. ovis, var. capræ, and var. cameli), two varieties of Psoroptes (P. longirostris, var. bovis and ovis), and Chorioptes spathiferus. This last is the true mange mite of the ox (or Symbiotes bovis of Gerlach). A variety of the follicle mite infests the sheep (Demodex folliculorum, var. ovis). Numerous species of tick (Ixodidæ) have been more or less fully described. Of these we have the Carapartos of the Portuguese (Ixodes bovis), attacking cattle; the I. reduvius, attacking sheep; the I. plumbeus, said to attack lambs; the I. albipictus and I. unipictus, found on the moose-deer. Probably this species also attacks cattle. A most horrible arachnidan is found on camels. I allude to Galeodes araneoides belonging to the Solpugidæ. This parasite will bite severely any person who attempts to dislodge it from the bearer. Turning to the insects, we find ruminants liable to be annoyed alike by flies (Diptera), fleas (Aphaniptera), and lice (Hemiptera). Various species of four different families of flies are apt to prove troublesome. Of the Œstridæ, attacking the ox, we have Hypoderma bovis, whose larvæ form tumours or warbles on the back; also H. lineata, Dermatobia noxialis, and Cephenomyia bovis (mihi). The larvæ of the latter reside at the root of the tongue and adjacent parts. In the sheep we have Œstrus ovis, Œ. purpureus, and Hypoderma lineata. Various species also attack goats and antelopes. Dr Kirk presented me with specimens of Œstrus from the frontal sinuses of a harte-beest or caama, and they have also been obtained from the sassabe, the saiga or colus, from the gnoo, and from the brindled gnoo, kokoon or gorgon. Mr Charles Danford presented me with several bots from an ibex. One or more species of Hypoderma have likewise been removed from the gazelle and other antelopes. The deer tribe are much attacked by bots. In the red deer we have Hyp. actæon and H. diana, a species also infesting the elk. The throat-grubs are Ceph. rufibarbis and Pharyngomyia picta; another species, also occurring in the fallow deer, Ceph. ulrichii, infests the elk, and C. stimulator the roe, the last-named deer being also infested by Hyp. diana. A throat-fly infests the reindeer, which is also frequently attacked by Hyp. tarandi. Specimens of the latter worm have been obtained by Dr Murie at the Zoological Gardens. The Hunterian Museum also contains these and other species of bots, presented by myself in Mr Andrew Murray’s name. A subcutaneous bot has been found in the musk-deer. A throat-bot (C. maculata) infests the dromedary.
In regard to the so-called free dipterous parasites and other noxious insects that attack ruminants, their name is legion. One of the worst is the tsetse (Glossina morsitans), immortalised by Livingstone. Of the Muscidæ we have the ox-fly (Musca bovina), the sheep-fly (M. cæsar), and the executioner (M. carnifex). Of the Tabanidæ we have T. bovinus and T. autumnalis, Chrysops cæcutiens, and the allied Asilus crabroniformis (Asilidæ). Amongst the specially noxious insects must also be placed Stomoxys calcitrans and Rhagio columbaschensis. This fly proves fearfully destructive to cattle in Hungary and Servia. Lastly, I can only further mention the common Melophagus ovinus. This is nothing more than a gigantic louse, which from long use agriculturists and veterinarians persist in calling the sheep-tick. It belongs to the Hippoboscidæ, the members of which family only attack quadrupeds and birds. As regards the lice (Anoplura), I have to mention Hæmatopinus vituli of the calf, H. eurysternus of cattle, and H. stenopsis of the goat; also Trichodectes scalaris, T. sphærocephalus, and T. capræ. These infest the ox, sheep, and goat, respectively.
For some account of the protozoal parasites (Psorospermiæ, &c.) infesting the flesh of ruminants I must refer the reader to Book I, Section IV, Part VI of this treatise.
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No. 864).—Idem, “On Hydatids of the Sheep,” in supp. to his paper on ‘Human Hydatids,’ in ‘Trans. of Soc. for the Improvement, &c.,’ vol. i, 1793, p. 34.—Huxley, “On the Anatomy and Development of Echinococcus (from a Zebra),” ‘Proc. Zool. Soc.,’ and ‘Ann. Nat. Hist.,’ 1852.—Karkeek, W. F., “Notes on the Rot (or iles of the Cornish graziers),” ‘Veterinarian,’ vol. iv, p. 573, 1831.—King, E., “On the Propagation of Rot (by means of the eggs of Fasc. hepatica) in Sheep,” ‘Veterinarian,’ vol. ix, p. 95, 1836.—Krabbe, “Husdyrenes Indvoldsorme,” ‘Tidsskrift for Vet.’ (See also my notice of the memoir in ‘Lond. Med. Rec.’ for 1872; repr. in ‘Veterinarian,’ May, 1873.)—Küchenmeister (see Bibl. No. 13).—Leaver, T., “Cases of the Husk (from worms) in Cattle,” ‘Veterinarian,’ vol. ii, p. 355, 1829.—Lepper, “Hydatids in the Kidney of a Lamb (with remarks by Prof. Varnell),” ‘Veterinarian,’ vol. xxxvi, p. 524, 1863.—Lewis (see Bibl. No. 13).—Lord, J., “On some of the Parasites principally affecting Ruminants,” ‘Trans. Vet. Med. Assoc.,’ 1842–43.—Masse (see Bibl. No. 13).—Mayer, T., “On Hoose in Cattle (from Filaria),” ‘Veterinarian,’ vol. xiii, p. 227, 1840.—M’Call, J., “On Sturdy in Sheep,” ibid., vol. xxx, p. 267, 1857.—Mégnin, P., “Le Str. minutissimus,” ‘Bullet. de la Soc. Centrale Vét.,’ in ‘Rec. de Méd. Vét.,’ July, 1878, and in ‘Ann. de Méd. Vét.,’ Oct., 1878, p. 563.—Moorcroft, “Brain Hydatids,” ‘Med. Facts and Observ.,’ 1792.—Morton, W. J. T., “On the Entozoa affecting Domesticated Animals, and particularly on Fasc. hepatica or Liver Fluke in Sheep,” ‘Veterinarian,’ vol. xii, p. 735, 1839.—Mosler (see Bibl. No. 13).—Murie, J., “On the occurrence of Œstrus tarandi in a Reindeer in the Zoological Society’s Gardens,” ‘P. Z. S.,’ 1866, with woodcuts.—Idem, “On a Leech (Trocheta) found in the Viscera of a Molluscan Deer (Cervus moluccensis, Müller),” ibid., 1865.—Numan, “Over den Veelkop-blaasworm der Hersenen” (this beautifully illustrated memoir, in the ‘Trans. of the Dutch Soc. of Sciences,’ supplies an elaborate bibliography of continental writings on Cœnurus cerebralis—T. S. C.), ‘Œrste Kl. Verh.,’ 3e Reeks, 2e Deel, p. 225 et seq.—Oliver (see Bibl. No. 13).—Padley, G., ‘On Entozoa from a Sheep;’ see Sandie.—Parsons, “On Diarrhœa in Lambs (with bronchial worms),” ‘Veterinarian,’ 1855, p. 685.—Patellani, “Sturdy in Cattle,” from ‘München Jahresbericht,’ in ‘Veterinarian,’ vol. xxx, p. 81, 1857.—Pellizzari (see Bibl. No. 13).—Perroncito (see Bibl. No. 13).—Pourquier (see Bibl. No. 13).—Ralph, T. S., “On the Parasitic Nature of Pleuro-pneumonia,” &c., two papers in ‘Austr. Med. Journ.,’ 1865.—Ranke, “Pulmonary Entozoic Disease of Sheep,” ‘Path. Soc. Trans.,’ 1858; see also ‘Veterinarian,’ vol. xxx, p. 708, 1857.—Raynaud, “A Word on the Cachexia, or Rot in Ruminants,” trans. from the ‘Journ. des Vét.,’ by W. Ernes, in ‘Veterinarian,’ vol. xxxiii, p. 488, 1859.—Read, R., “Destruction of Strongylus and Filaria in the Bronchial Passages of Calves, through nasal inhalation of ether, chloroform, oil of turpentine, or rectified oil of amber,” ‘Veterinarian,’ vol. xxi, p. 604, 1848.—Reck (see De Reck).—Reed, R., “Congenital Hydatids in a Lamb,” ‘Veterinarian,’ vol. viii, p. 551, 1835.—Rhind, “Description of a species of Worm (Pentastoma) found in the Frontal Sinus of a Sheep,” ‘Farrier and Naturalist,’ vol. iii, p. 277, 1830, and ‘Lancet,’ 1829.—Robertson, “Remarks on Tænia in Lambs,” ‘Rep. of Scottish Med. Vet. Soc.,’ in ‘Veterinarian,’ 1875, p. 80.—Rochard (see Bibl. No. 13).—Rose, C. B., “On Cœnurus and Acephalocysts,” ‘Lond. Med. Gaz.,’ vol. xxiv, p. 525, 1844.—Idem, “On the Anat. and Physiol. of the Cysticercus tenuicollis,” ‘Roy. Med.-Chir. Soc. Trans.,’ and ‘Lancet,’ 1848.—Idem, “On the Vesicular Entozoa, and particularly Hydatids,” ‘Lond. Med. Gaz.,’ vol. xiii, p. 204, 1833–34.—Sandie (with Padley), “On Entozoa in the Lungs of a Sheep,” ‘Ann. Nat. Hist.,’ 1849.—Schwarzmeier, “Die Trepanation des Rindes bei Cœnurus,” ‘Wochenschr. f. Thierheilk.,’ 1875, s. 295.—Shenton, “Worms from the Stomach of a Cow,” ‘Veterinarian,’ 1844, p. 487.—Siedamagrotzky, “Hydatids in the Liver of a Cow,” ‘Bericht üb. das Veterinawesen im Kön. Sachsen,’ 1875, s. 29.—Simonds, J. B., “Death of Sheep from Worms in the Stomach (abomasum), being remarks on Mr. Haywood’s case,” ‘Veterinarian,’ vol. xxxiv, p. 525, 1861.—Idem, ‘The Rot in Sheep, its nature, cause, treatment, and prevention,’ London, 1862.—Idem, “On Filariæ in the Bronchi of Calves,” ‘Trans. Vet. Med. Assoc.,’ 1843, p. 517.—Idem, “On Strongylus in the Bladder and Intestines,” ibid., 1843.—Idem, “On Hydatids of the Liver of a Sheep (Mr Scruby’s case),” ibid., p. 331.—Idem, “On Disease of the Mesenteric Artery from Strongyli within the Vessel,” ‘Path. Soc. Trans.,’ 1854.—Idem, “Lecture on the Nature and Causes of the Disease known as Rot in Sheep,” vol. xxxiv, p. 274, 1861.—Spence, G. W., “On Œstrus of the Ox,” ‘Edin. Med. Journ.,’ 1858, and ‘Edin. Vet. Rev.,’ vol. i, p. 400.—St Cyr (see Bibl. No. 13).—Stoddart, J., “Case of Hydatids in the Liver (of a Cow),” ‘Veterinarian,’ vol. xi, p. 637, 1838.—Sutton (Lecture), ‘Gardiner’s Chronicle,’ June 29, 1872.—Sylvester, F. R., “Cases of Parasites infesting the Brains and Intestines of Lambs,” ‘Vet. Rec.,’ vol. ii, p. 40, 1846.—Thudichum (see Bibl. No. 13).—Idem, “Echinococci from the Sheep’s Lungs,” ‘Rep. Med. Soc. Lond.,’ in ‘Assoc. Med. Journ.,’ 1856, p. 195.—Tommasi (see Bibl. No. 13).—Van Beneden, “On the Development of Cœnurus,” from ‘Comp. Rend.,’ in ‘Ann. Nat. Hist.,’ vol. xiv, 1854.—Watson, K. W., “Experiment for the Cure of the gidd (Cœnurus) in a Sheep,” ‘Lond. Med. Repos.,’ 1815.—Willemoes-Suhm, in ‘Sieb. and Köll. Zeitschr.,’ Bd. xxv, s. 176.—Wilson, E., “On the Anatomy of Trichocephalus affinis,” ‘Vet. Rec.,’ 1846.—Wymann, “Note on Filaria in the Bronchi of a Sheep,” see Anon. on “Entozoa and Parasites,” in ‘Amer. Journ. Sci.,’ vol. xxxix, p. 183, 1840.—Youatt, “On Hydatids in the Sheep (symptoms, prevention, treatment, &c.),” ‘Veterinarian,’ vol. ii, p. 519, 1834.—Idem, “On the peculiar Bronchitis in young Cattle, accompanied by Worms in the Bronchial Passages,” part of lecture, in ‘Lancet,’ 1832.—Idem, “Hydatids in the Brain of a St Domingo Goat,” ‘Veterinarian,’ vol. ix, p. 443, 1836.—Idem, “Bronchitis from Worms (in Cattle),” ibid., vol. vi, p. 177, 1833.—Idem, “Hydatids in the Brain (in Cattle),” ibid., vol. vii.—Yvart, “Brain Hydatids,” ibid., 1828, p. 19.—Zahn, “Lungenwürmer beim Reh,” ‘Œsterr. Vierteljahrschr. f. w. Vet.,’ 1875, s. 125.—Zurn (see Bibl. No. 13).—For further references to the literature of Hydatids in Animals, see Bibliography No. 20, o, in the first half of this work.
It will naturally be expected that I should give a full account of the parasites of the solipedal, solidungulate, or equine mammals. As regards the horse I regret that I cannot meet this expectation in so complete a manner as the subject deserves; nevertheless, with the aid of an extended bibliography the summary here offered will be found to be tolerably exhaustive. At all events I think I may say that no similar record has hitherto been attempted.
The liver fluke (Fasciola hepatica), though not very frequent in the horse, is not uncommon in the ass. In dissecting-room subjects at the Royal Veterinary College it is often encountered. In France it was originally found in the horse by Daubenton. As I learn from Sonsino, Dr Abbate Bey recently recorded a similar find at Cairo. In solipeds generally the liver fluke appears to be almost harmless, for, notwithstanding the frightful ravages produced by rot amongst a variety of animals besides sheep, we have no evidence of the destruction of horses from this cause. In the German outbreak of 1663–65 multitudes of cattle and deer perished, and in the French outbreak of 1829–30 five thousand horned beasts succumbed in the arrondissement of Montmédy alone. In neither of these epizoötics were the solipeds affected. More importance attaches itself to the study of the amphistomatoid flukes. These parasites, though in a scientific sense only recently discovered in equine bearers, have been long known to the natives of India. They appear to be capable of producing serious intestinal irritation. I have described two forms (Amphistoma Collinsii and A. Coll., var. Stanleyi), which infest the colon. The specimens sent to Prof. Simonds from India by Mr Stanley, V.S., were much larger than those sent to me from Simla by Mr Collins, V.S., some ten years later (1875). As in all other amphistomes obtained from the intestines of elephants and cattle, the worms, when fresh, were of a bright brick-red color. By the natives of India these parasites are called Masuri; but no description of the worms had been published prior to the account which I gave of the contributions forwarded by Major-General Hawkes, Mr Collins, and Mr Stanley.
I shall have occasion to speak of the elephant’s Masuri further on; but in the meantime I must remark that the generally received notion as to the parasitic cause of the earth-eating propensities of various animals seems to have some foundation in fact. Not alone from Major-General Hawkes in Madras, from Mr Folkard in Ceylon, and from various other trustworthy sources, have I been informed of this habit on the part of Indian horses, but Dr Rowe told me that Australian horses, and even sheep, infested with stomach-worms, are in the constant habit of consuming large quantities of sand. From all the facts that have come before me, I am inclined to think that gastric or intestinal irritation, however brought about, may induce the habit in question, parasites being only one of the many sources of irritation giving rise to symptoms of colic in solipeds and pachyderms alike. At all events the African elephants at the London Zoological Society’s Menagerie, as repeatedly witnessed by myself, are in the habit of swallowing large quantities of soft mud during the summer months, but no traces of masuri have as yet been detected in their fæces.
When by letter I informed Major-General Hawkes of an interesting find by Mr Collins of about a thousand Amphistomes in the colon of a horse that had died at Simla, the announcement called forth a reply which is sufficiently instructive to be quoted. Writing from Secunderabad in July, 1875, he says, respecting this “find:”—“Your statement has incidentally thrown light upon a subject which has puzzled many of us in this country. It occasionally happens that a horse, on being opened after death, is found to have accumulated in his intestines large quantities of sand and gravel. In a recent case this accumulation amounted to 1412 lbs. Until recently it was always held that this gravel or sand could only be introduced with the animal’s food. All grain in this country is trodden out by bullocks on an earthen floor, and the grain undoubtedly contains a proportion of sand and gravel derived from this source. Although this ought to be carefully washed out before it is given to the horse, still, owing to the carelessness of the native horse-keepers, this cleaning is, I expect, often omitted. In the daily ‘feed’ of eight or ten pounds of grain given to each horse the utmost quantity of sand or gravel that could be found admixed therewith would not probably exceed two or three ounces; consequently it would take from 77 to 116 days to accumulate so large a quantity as 1412 lbs. Now, the advocates of the theory of the gradual accumulation of sand in this way have never been able to explain why the grain, grass, hay, and other ingesta should pass in the ordinary way through the intestines, whilst this sand or gravel remains behind. One can understand the possibility of such substances as wool, hair, or similar matters concreting in the alimentary canal, though I believe they are usually found in the stomach, and not in the intestines; but how a most incohesive substance like sand can possibly accumulate in the gradual way required by their theory I have never heard even plausibly explained. On the other hand, the fact that horses are often excessively addicted to eating earth is well known; and if my memory serves me correctly, it was found necessary, about twenty years ago, to remove the mud-walls of the pickets surrounding some of the horses of a mounted corps in this presidency in consequence of this habit. Now, given the fact that the amphistoma has been found in the horse (as your specimens prove), may we not fairly suppose it possible that the animal resorts to the same mode of ridding himself of this parasite as does the elephant? and also, would it not in a much more natural manner account for the large quantity of gravel or sand found in the intestines than does the theory of gradual accumulation? Reasoning from analogy, as in the case of the elephant, this eating of earth in the horse would be an instinctive effort on the part of the “host” to rid himself of the parasite. This self-taken remedy is doubtless in many cases quite effectual, though unnoticed. The fatal cases are probably those in which the horse has either overdone the remedy or where the system was too debilitated to carry off a quantity of sand or gravel that would otherwise have safely passed through the intestines of a horse in more robust health. The actual fact must, of course, be verified by careful investigation.”