Chapter XXXVI: Part IX: (solidungula) (2)

Passing to the consideration of other intestinal nematodes, the next in importance is the large lumbricoid (_Ascaris megalocephala_) found in all solipeds, including the zebra. Whilst the male worms rarely exceed seven inches in length, the females sometimes reach seventeen inches. Science is indebted to Schneider for setting at rest all doubt as to the specific distinctness of this worm. The far larger number of caudal papillæ at once distinguishes it from the lumbricoid of man and the hog. The equine Ascaris may occur in any part of the alimentary canal, but the small gut forms its proper head-quarters. The entire course of development of this worm has not been traced; nevertheless, Heller found human lumbricoids measuring less than the eighth of an inch. It is not likely that any intermediate host is necessary for the growth of the larvæ, prior to their access to the definitive host. I have reared the larvæ in impure water and in moist horse-dung, up to the size of 1/30 of an inch. They were then furnished with a completely-formed digestive apparatus. Davaine kept the intra-chorional embryos alive in water for five or six years. His experiments on rats, dogs, and on a cow, led to no decisive results; but it is important to know that the eggs of lumbricoids effectually resist dryness. According to Davaine, however, embryonal development is thus arrested (except in _Ascaris tetraptera_ of the mouse).

Seeing how readily the most ordinary attention to cleanliness must suffice to prevent lumbricoid helminthism, it is scandalous that so many severe cases of disease from this source should ever and anon turn up and be reported. In no properly conducted stable are these large entozoa ever to be seen in any considerable numbers; for so long as the water-supply is good and the fodder clean there is no possibility of infection. A fertile source of infection, however, results from allowing horses to drink at foul road-side ponds and from open waters in the vicinity of stables and paddocks where foals are reared. Into the clinical bearings of the subject I do not enter, but a host of interesting records of lumbricoid disease may be found in veterinary journals, both home and foreign. These have their counterpart in the very similar cases recorded in the medical journals, and quoted by me in the 34th bibliography of this work. From Sonsino’s report these worms do not appear very common in Egypt, but the veterinary inspector, Dr Zunhinett, had occasionally met with them. From Messrs W. Awde, J. B. Wolstenholme, and other English veterinary surgeons, I have received notes of interesting cases, but in this connection I can only further refer to the published cases of Messrs Anderson, Boddington, Cartwright, Harrison, Moir, and Wallis. The French cases, by M. Cambron and by M. Véret, are particularly instructive. Many of the cases give fatal results. In one fatal instance a pupil of mine counted over 1200 of these worms, and in a similar fatal case Mr Lewis reports that he found the small intestine literally crammed, some thousands of worms being huddled together in large masses.

The next nematode of general interest is the pinworm (_Oxyuris curvula_). Professional men often confound it with the palisade worm, and it has even been mistaken for the rat-tail maggot (_Helophilus_). The longest males measure 1-3/4″, and the females often beyond 4 inches. This worm infests the colon in great numbers, the species being easily recognised by its long subulate tail. Like its much smaller congener infesting man, this worm occasions severe local irritation, clusters of the eggs often accumulating to form yellow incrustations at the verge of the anus. Equine pinworms are vegetable feeders, and, like human Oxyurides, are conveyed to the bearer in a direct manner. No horse properly looked after can be infested by these worms. Local washings and stable cleanliness being secured by an attentive groom, the animals are safe. Prophylactic measures of this kind are all-powerful against infection. Notwithstanding the ease, however, with which the oxyuris disorder may both be prevented and cured, we find it prevails extensively everywhere, alike in mankind and in solipeds. Dr Sonsino found these parasites abundant in Egypt, some of the worms reaching a length of nearly five inches (120 mm.). Mr Emmerson has given an interesting account of the prejudicial effects of these entozoa in the horses of Singapore.

One of the most remarkable equine parasites is that which I am in the habit of calling the large-mouthed maw-worm (_Spiroptera megastoma_), in contra-distinction to the small-mouthed species (_S. microstoma_). In this country the worm has attracted little notice, but through the kindness of Mr Spooner Hart, of Calcutta, and of Mr Percivall, of the 11th Hussars, stationed at Umballa, I have had abundant opportunities of examining this entozoon and the singular pathological appearances which it occasions. This parasite was first described by Rudolphi, who says:--“Spiroptera capitis discreti ore magno nudo, cauda feminæ rectiuscula acuta, mavis simpliciter spirali, corpusculis rotundis ad basim penis styliformis.” The worm was afterwards observed by Schultze, Chabert, and frequently also by Andral, but the best accounts of it are those given by Gurlt, Valenciennes, and Dujardin. Schneider has likewise done much to set at rest disputed points. Respecting the _Spiroptère du Cheval_, Dujardin, writing in 1844, observes that “Rudolphi at first studied this helminth from examples found in great number by Reckleben, at Berlin, in tubercles of the stomach of two horses. Quite recently, M. Valenciennes, at Paris, has found it frequently in tumours, from twenty to forty millimètres in size, in the stomach of eleven horses out of twenty-five that he had subjected to this kind of research. These tumours, lodged between the mucous and muscular layers of the digestive canal, are perforated by several holes traversing the mucous membrane. They are divided internally by a number of folds into numerous intercommunicating cavities, and sometimes filled with solid mucus and very many spiropteras. It is from examples collected by M. Valenciennes that I have been able to study the parasite.”

As regards the description of the worm, it is almost needless to say that Dujardin’s account is minute and admirable in all respects. In fact, no naturalist ever exceeded the Rennes _savant_ in carefulness and accuracy of detail. An interesting point connected with these stomach-worms lies in the circumstance that Gurlt recognised two varieties, one of which he termed _Sp. meg._, var. _major_. It remained for Schneider to show that the larger worms formed an altogether distinct species, which he termed _Filaria microstoma_ (‘Monogr.,’ l. c., 1866, s. 98). It was not unnatural that Rudolphi and his successors should confound these two forms together, and it is also not a little curious that the smaller of the two species has the larger mouth. Practically, veterinarians will probably rest content to know that whilst the _Spiroptera megastoma_ occupies tumours in the walls of the stomach, the _S. microstoma_ is always to be found free in the cavity of that organ. Any helminthologist who may chance to have read the Ceylon Company’s report on the fatal epidemic affecting the mules of the Mauritius in 1876 can scarcely fail to have observed that the worm called _Ascaris vermicularis_ by Mr Bradshaw is none other than our _Sp. megastoma_. The description of the tumours as “reticulated” sufficiently explains their honeycomb-like appearance, but I think that the expression “alveolar” would better convey their true pathological character. Mr Spooner Hart compared these structures, which he terms “abodes,” to mole-hills, but there is no good ground for supposing that the wanderings of the parasites are in any sense comparable to the burrowings of the mole. In like manner the expression “nidus,” employed by Mr Bradshaw, though suggestive of their nest-like appearance, is to some extent misleading, as it implies that the worms form a nide or brood. Possibly, it may turn out that all the nematodes in each tumour have been bred in the spot where they are found, but hitherto they have only been seen in the adult state. Earlier stages of growth should be diligently sought for. Widely dissimilar as the two maw-worms are, it would not greatly surprise me to learn that _Sp. megastoma_ and _S. microstoma_ are dimorphic conditions of one and the same entozoon. At all events, Ercolani’s determination of the relations subsisting between _Ascaris inflexa_ and _A. vesicularis_ suggests a possible analogy of this kind. I may mention that the male _Spiroptera megastoma_ reaches nearly one third and the female one half of an inch in length. A constriction separates the head from the body. The mouth is surrounded by four thick horny lips, the dorso-ventral pair being the larger. The tail of the male is spirally twisted, and furnished with lateral bands supported by three or four ribs. It carries two curved spicules of unequal size. There are five pairs of caudal papillæ, the tail being bluntly pointed in both sexes. The vulva of the female is placed about 1/7″ below the head. The eggs are linear or very narrow, and furnished with thick shells. According to Sonsino, who found _Sp. megastoma_ in five out of sixteen Egyptian horses, the verminiferous growths are usually seated near the pyloric end of the stomach, as many as four tumours occurring at one time. Neither Sonsino nor any other observers already quoted appear to think that these morbid changes in any way interfere with the healthy performance of the gastric functions. However, I am of opinion that at least one recorded fatal case of parasitism, producing rupture of the stomach, affords an instance, however rare, of the injurious action of this entozoon. It is reported under the signature of “Argus,” quoted below.

In this connection I may mention that in 1864 Prof. Axe observed some small worms, scarcely visible to the naked eye, in the mucous membrane of the stomach of a donkey, the same worms being subsequently observed in three other donkeys brought to the dissecting room of the Royal Veterinary College. From the examination of a drawing of one of the male worms, executed by Prof. Simonds, I am led to believe that the parasites are entirely new to science. The hood being well marked there can be no doubt as to the strongyloid affinities of the worm. I therefore propose to call the worm after its discoverer (_Strongylus Axei_).

In regard to _Sp. microstoma_, the males measure up to 2/3″, whilst the females have a long diameter of 3/4″ or rather more (10‴). The small-mouthed maw-worm lives free in the stomach, and, as Krabbe observes, not unfrequently in very considerable numbers. It does not appear to be capable of injuring the host.

One of the most interesting equine nematodes is the eye-worm. Most veterinary writers speak of it as the _Filaria oculi_, but to helminthologists it is better known by the more correct designation, _F. papillosa_. Though commonly obtained from the eyeball and its tunics, the worm infests various tissues and organs of the body, being found in the thorax, abdomen, membranes of the brain, muscles, and cellular tissues. It infests the ass and mule, and also horned ruminants. The males attain a length of three inches and the females seven inches. The head is broad, with a gaping mouth armed with a ring of chitine and two prominent denticles. There are also two papillæ on the neck near the middle line, besides sixteen caudal papillæ, eight on either side. The tail of the male is spirally twisted, that of the female only slightly curved. Notwithstanding the many opportunities afforded of examining this parasite in the fresh state, very little is known respecting its origin and course of development. Dr Manson, who found that the mouth was armed with a five- or six-toothed oral saw, considers that the eye is not a proper resting place for the parasite, and that when one wandering worm comes across the track of another it follows it up from sexual instinct, and thus several may be found together in one place. The tracks are readily seen by the naked eye. Dr Sonsino speaks of it as a “yellow line.” This Italian observer found the worm in twelve out of the sixteen solipeds he examined during the plague. Each horse showed from two to a dozen worms “in the peritoneal cavity, wandering free on the serous lining, without causing any apparent mischief to the membrane.” On one occasion Sonsino found the worm in the liver. From the similarity of habit there can be little doubt that the cases of guinea-worm (_F. medinensis_) recorded by Clarkson and others, as occurring in the horse, were merely examples of _F. papillosa_. I think so all the more because the lamented Fedschenko verbally expressed to me his astonishment that I had in my introductory treatise (p. 387) spoken of the Dracunculus as an equine parasite. I did so on the authority of others. To the Rev. Horace Waller I am indebted for specimens of the eye-worm brought from Assam, and to Mr Spooner Hart for others sent from India. For examples occurring in England I am indebted to Mr Haydon Leggett, who, in 1875, sent me three specimens extracted from the eye of a five-year-old mare. Mr Steel has also given me an example of _F. papillosa_ taken from the peritoneum of a donkey. Similar cases are constantly occurring in the practice of veterinarians in Hindostan. Highly interesting Indian cases are recorded by Kennedy, Molyneux, Twining, and Breton, and in addition to these I may also particularise those of Macnamara, C. Percivall, Hickman, Clarkson, Skeavington, and Jeaffreson. The cases by Lee and Grellier also deserve attention.

Another species of thread-worm (_Filaria lacrymalis_) is occasionally found in the horse between the lids and eyeball. It is a comparatively small and harmless parasite, the males measuring 1/2″ in length and the females 2/3″. It also infests the ox. Both the large and small eye-worms are viviparous, and, not improbably, both of them are the means of conveying embryonic Filariæ into the circulation. Be this as it may, we owe to Dr Sonsino the discovery of hæmatozoa in an Egyptian horse. The larval worm was provisionally named by him _Filaria sanguinis equi_. The microscopic nematodes closely resemble the larvæ of _F. sanguinis hominis_, but they are smaller. The horse from whose blood Dr Sonsino obtained the minute worms was also found, by post-mortem examination, to have been infested by _Filaria papillosa_, a circumstance which naturally suggested a genetic relation between the larval and adult parasites. Similar, if not the same, microscopic worms had been previously discovered by Wedl, who primarily and independently regarded them as embryos of _F. papillosa_. Another curious filaria-like entozoon is the reticulated threadworm (_Onchocerca reticulata_). In England we have no acquaintance with this singular parasite, but it appears to be tolerably common in Italy. Excellent figures of it have been given by Diesing. Both males and females are in the habit of coiling themselves within the muscles, where they are found invested by a capsule of connective tissue. When unrolled the sexes are found of equal size, acquiring a length of 1-1/2″. The worm has a simple unarmed mouth, its body being marked by a series of annulations formed of incompletely anastomosing rings. It does not appear to possess any clinical importance.

In connection with the equine nematodes I need only mention the lung-worm (_Strongylus micrurus_). Its importance in relation to the production of husk or parasitic bronchitis in calves has already been considered. The worm is rarely productive of mischief amongst solipeds, nevertheless, in the dissecting-room subjects at the Royal Veterinary College, the presence of these parasites in the lungs is frequently noticed. Lastly, it only remains for me to observe that the renal strongyle (_S. gigas_) is occasionally seen in the horse. In 1792 M. Chabert found one in the left kidney, and similar cases have since either been witnessed or reported by Rudolphi and Leblanc.

Of the numerous insect parasites and tormentors of solipeds the gadflies (_Œstridæ_) demand chief attention. For special description of the forms, Brauer’s monograph is the most, and, in fact, the only reliable authority. Here it is not possible to give the characters of the various equine species, of which at least half a dozen are known to science. As remarked by me in the special chapter contributed to Prof. Williams’ well-known veterinary treatise, the common gad-fly (_Gastrophilus equi_) attacks the animal whilst grazing late in the summer, its object being, not to derive sustenance, but to deposit its eggs. This it accomplishes by means of a glutinous excretion, causing the ova to adhere to the hairs. The parts selected are chiefly those of the shoulder, base of the neck, and inner part of the fore legs, especially about the knees, for in these situations the horse will have no difficulty in reaching the ova with its tongue. When the animal licks those parts of the coat where the eggs have been placed, the moisture of the tongue, aided by warmth, hatches the ova, and in something less than three weeks from the time of the deposition of the eggs, the larvæ make their escape. As maggots they are next transferred to the mouth, and ultimately to the stomach along with food and drink. A great many larvæ perish during this passive mode of immigration, some being dropped from the mouth, and others being crushed in the fodder during mastication. It has been calculated that out of the many hundreds of eggs deposited on a single horse, scarcely one out of fifty of the larvæ arrive within the stomach. Notwithstanding this waste the interior of the stomach may become completely covered with “bots.” Whether there be few or many, they are anchored in this situation chiefly by means of two large cephalic hooks. After the bots have attained perfect growth they voluntarily loosen their hold, and allow themselves to be carried along the alimentary canal until they escape with the fæces. Many persons suppose that during their passage through the intestinal canal they re-attach themselves to the mucous membrane, thereby occasioning severe intestinal irritation. This is an error. In all cases they sooner or later fall to the ground, and when transferred to the soil they bury themselves beneath the surface, in order to undergo transformation into the pupa condition. Having remained in the earth for a period of six or seven weeks they finally emerge from their pupal-cocoons as perfect dipterous insects. It thus appears that bots ordinarily pass about eight months of their lifetime in the digestive organs of the horse.

That they are capable of giving rise to severe disease there can be no doubt, but it is not often that the disorder is correctly diagnosed, since it is only by the passage of the larvæ that the practitioner can be made aware of their presence. Mr J. S. Wood has published a case of tetanus in a mare, associated with the larvæ of _Œstrus equi_, and Mr J. T. Brewer has also given a case where the duodenum was perforated by bots. Mr Goodworth records an instance of pyloric obstruction from the same cause, and Mr W. Coupe informed me in 1876 that he had a drove of foreign ponies under his care, all of which suffered irritation from hæmorrhoidal bots. He removed them with a pair of forceps. Although frequently said to do so, the common bot does not attach itself to the rectum before finally escaping the host. The larvæ of _G. hæmorrhoidalis_ normally reside there. In this situation they seriously inconvenience the bearer. The bots of _G. nasalis_ are often confounded with those which ordinarily occupy the stomach of the bearer. The larvæ of _G. nasalis_ commonly reside in the duodenum near the pylorus. According to Schwab and Brauer, they rarely occupy the stomach. As occurs in the common species, this bot passes away with the fæces, and does not attach itself to the lower bowel. The bots of Brauer’s _G. inermis_ much resemble those of _G. equi_, but they are much smaller and attach themselves to the wall of the small intestine. The bots of _G. pecorum_, which dwell in the rectum, are readily recognised by their peculiar form and scanty spination. They are pointed in front and truncated posteriorly. An assinine variety of _G. equi_ has been described by Bilharz, whilst another distinct species (_G. flavipes_) attacks the ass and mule. The bot-larvæ of the latter host require recognition and description. A great variety of other equine bot-flies have been described, but all, or nearly all, of them are mere synonyms of the above-mentioned forms. For the limitation of the species I accept Brauer’s authority, and likewise his nomenclature. A great deal of nonsense has been written respecting bots. It is a relief to believe that _G._ (Œstrus) _veterinus_, _G. ferruginatus_, _G. jubarum_, _G._ (Œ.) _Clarkii_, _G. salutiferus_, _G. subjacens_, and many others, are not good species, at least that they are mere synonyms. In regard to the occurrence of subcutaneous bot-like maggots in the horse and ass, no doubt need exist on this point. I am indebted to Mr Percy Gregory for characteristic specimens taken from the back, neck, and withers of a four-year-old gelding. They appear to correspond with the _Hypoderma Loiseti_ of Joly. Similar maggots have been found in the ass by Herr Erber, but Brauer refers these to _H. silenus_. Prof. Brückmüller published a case where the brain was infested by larvæ; and Mr Shipley has sent me an example of _H. equi_, which he states he removed from the choroid plexus of the brain. In addition to the cases by Woods, Goodworth, and Brewer, already quoted, others have been published by Tyndal and Cartwright.

Amongst the numerous other parasitic dipterous larvæ one must notice the rat-tailed maggots (_Helophilus_). A genuine instance of this kind has been brought under my observation, but the example recorded by Professor Axe was spurious. Professor Simonds and myself saw this supposed maggot, which was merely a very stout and pregnant _Oxyuris curvula_. Another genuine case was published by Mr. Stanley. This is quoted by A. Numan in his essay on _Cœnurus_. I have previously mentioned my having received an Helophilus-larva that had passed from the human body. One of the most troublesome external parasites is the so-called horse-tick or forest-fly (_Hippobosca equina_). They attack the abdomen, flanks, and inner part of the thighs in great numbers, occasioning great distress to the bearer. Being of leathery toughness their bodies are not easily crushed, and they are removed only with great difficulty. There is an equine disease in Sweden called _Stackra_, which is erroneously attributed to injuries produced by a species of fly-maggot (_Lixus_) which lives on the fine-leaved water-drop wort (_Phellandrium_). As regards the so-called free parasites, or rather non-parasitic obnoxious insects, which torment solipeds, it is impossible even to enumerate them. The tsetse of South Africa (_Glossina morsitans_) is terribly fatal to the horse, but it is said that the mule, ass, and zebra do not suffer from its bites--an immunity shared by swine, goats, antelopes, and man himself. Major Vardon’s rash experiment (based on the supposition that horses deprived of fresh green food would not suffer from the attacks of the fly) proved fatal to an animal which he purposely exposed on a much infested hill-top. The horse died ten days after it was bitten. According to Chapman, the bites of four tsetse flies are sufficient to kill an ox, but in man the irritation produced is very slight. Amongst other insects proving troublesome to solipeds may be mentioned the leg-sticker (_Stomoxys calcitrans_), the clegg (_Hæmatopota pluvialis_) which is very abundant in the West Highlands, various species of _Tabanidæ_ and _Asilidæ_ (_Tabanus autumnalis_, _T. bovinus_, _Chrysops cæcutiens_, _Asilus crabroniformis_), and also a host of ordinary flies and gnats (_Muscidæ_ and _Tipulidæ_), as, for example, _Anthomyia meteorica_ and _Culex equinus_. In India the bite of a species of _Simulia_ gives rise to the formation of open sores of the most intractable character. As regards hemipterous insects it may be said that many species of lice (_Anoplura_) produce what is called phthiriasis or lousiness in the horse, some of them being derived from poultry. The best known species are _Trichodectes equi_, _T. scalaris_, _Hæmatopinus equi_, _H. vituli_, _H. eurysternus_, and the ass-louse (_H. asini_). Of the half dozen or more species infesting the hen (belonging to the genera _Goniocotes_, _Liotheum_, &c.) it is not probable that more than one or, at most, two of them are concerned in the production of poultry-lousiness in the horse. As an equine disorder this kind of phthiriasis was first described by Bouley. Cases in England have been observed by Messrs. Henderson, Moore, and Woodger. For some account of cases of lousiness due to _Hæmatopinus_ I am indebted to Mr S. Butters. As regards the scab, itch, and mange insects or mites (_Acaridæ_), three perfectly distinct forms are known. Adopting M. Mégnin’s classification they are _Sarcoptes scabiei_, var. _equi_, _Psoroptes longirostris_, var. _equi_ (being the _Dermatodectes equi_ of Gerlach), and _Chorioptes spathiferus_, var. _equi_, which is the _Symbiotes equi_ of Gerlach. All the species have been beautifully illustrated by M. Mégnin, whose memoir has dispersed many of the clouds of error and misrepresentation which have hitherto surrounded the subject. Whilst _Psoroptes_ forms the true horse-mite, and attacks various parts of the body, _Chorioptes_ confines its attacks to the posterior regions. Messrs South and Day and myself have verified some of the facts recorded by Mégnin in respect of the structure and habits of this last species. Another kind of mite (_Glyciphagus hippopodos_) is stated to infest the ulcerated feet of horses. It would appear that no true ticks properly belong to solipeds; nevertheless, the common cattle-tick (_Ixodes bovis_) occasionally attacks horses. Probably several other species of Ixodidæ, known to infest other animals, behave in the same way. The Arachnidan called _Pentastoma tænioides_, though properly belonging to the dog, has on several occasions been detected in the nasal or frontal sinuses of the horse. Such instances are recorded by Chabert and Greve. The largest example of this singular entozoon seen by myself was obtained from the same situation, and presented to me by the late Mr C. B. Rose, whose writings I have frequently quoted in connection with the _Cœnuri_ of rabbits.

BIBLIOGRAPHY (No. 50).--_Aitken, J._, “Worms in the Spermatic Artery of a Colt,” ‘Veterinarian,’ p. 683, 1855.--_Anderson, J._, “A Case of Strangulation of the Ileum (with Lumbrici),” ‘Veterinarian,’ p. 261, 1859.--(Anonymous), “Rupture of the Stomach, associated with the existence of Cysts between its Coats containing Worms,” ‘Veterinarian,’ March, 1864, p. 151.--(Anon.), “Extraction of _Filaria oculi_ from the Horse,” by “Miles,” ‘Veterinarian,’ 1864, p. 218.--(Anon.), “Case of _F. oculi_ in the Horse,” ‘Veterinarian,’ 1864, p. 218.--(Anon.), “Worms in the Coats of the Stomach of a Horse,” by “Argus,” in the ‘Veterinarian,’ 1865, p. 151.--_Baird, W._, “Notice of _Sclerostoma_ in the Testicle of the Horse,” ‘Proc. Zool. Soc.,’ 1861.--_Blanchard_, “_Anoplocephala perfoliata_,” ‘Ann. des Sci. Nat.,’ 3rd ser., tom. x, p. 345.--_Bollinger, O._, ‘Die Kolik der Pferde und das Wurmaneurisma der Eingeweidearterien,’ Munchen, 1870. (Reviewed by myself in the ‘Veterinarian,’ Jan.-April, 1874.)--_Bovett_, “Existence of Filariæ in a Sinuous Ulcer of the Withers of a Mare,” ‘Veterinarian,’ p. 515, 1861.--_Bradshaw, C._, “Death of Mules from Parasitic Disease in the Mauritius (with remarks by Dr Cobbold),” ‘Veterinarian,’ Dec., 1876, p. 837.--_Brauer, F._, ‘Monographie der Œstriden,’ Wien, 1863.--_Idem_, “_Œstr. (Hypoderma) Clarkii_,” in ‘Verhandl. der zool.-bot. Gessellsch. in Wien,’ xxv, p. 75.--_Idem_, “On _Cephenomyia trompe_ from the Reindeer,” _ibid._, p. 77.--_Idem_, “_Hypoderma bonassi_ from the American Buffalo,” _ibid._ (all with figs.), 1875.--_Breton_, “On the Worm found in the Eye of the Horse,” ‘Calcutta Med. and Phys. Soc. Trans.,’ vol. i, 1825, p. 337.--_Brown, D. S._, “The _Œstrus equi_, or Horse-bot,” the ‘Veterinary Journal,’ July, 1877, p. 14.--_Brückmüller_, “Larvæ in the Brain of a Foal,” from ‘Viert. für wissensch. Vet.,’ in ‘Veterinarian,’ p. 82, 1857.--_Cartwright, W. A._, “On Strangulation of the Bowels, associated with about 150 Bots, and also some 150 Ascarides, in the Horse,” ‘Veterinarian,’ p. 413, 1833.--_Idem_, “Case of about 200 ‘Bots in the Œsophagus’ of a Horse,” _ibid._, p. 400, 1828.--_Chambron_, “On a Parasitic Malady in the Horse,” from ‘Ann. de Méd. Vét.,’ in ‘Edin. Vet. Rev.,’ 1861; see also (_Cambron_) ‘Veterinarian,’ 1860, p. 612.--_Clark, B._, “Obs. on the genus Œstrus,” ‘Linn. Trans.,’ vol. iii, p. 289, 1797.--_Idem_, ‘An Essay on the Bots of Horses and other Animals,’ London, 1815.--_Clarkson, N. F._, “Case of _Filaria oculi_ in the Horse,” ‘Vet. Rec.,’ vol. i, p. 73, 1845.--_Idem_, “Case of _Filaria medinensis_ in the Horse,” _ibid._, 1845.--_Cobbold_, “On the Diptera (bots),” in a chap. on the Parasitic Diseases of Animals, in Williams’ work (l. c., Bibl. No. 48).--_Idem_, “Obs. on rare Parasites from the Horse,” ‘Veterinarian,’ Feb., 1874.--_Idem_, “Further remarks on rare Parasites from the Horse,” _ibid._, April, 1874.--_Idem_, “Fatal Epid. affecting Ponies,” _ibid._, June, 1874.--_Idem_, “Remarks on Mégnin’s Tapeworm,” _ibid._, Sept., 1874.--_Idem_, “Report on Parasites (sent from India by F. F. Collins and Spooner Hart),” _ibid._, Nov., 1874.--_Idem_, “Epizoöty in the Horse, more especially in relation to the Ravages produced by the Four-spined Strongyle (_S. tetracanthus_),” _ibid._, April, 1875.--_Idem_, “The Egyptian Horse Plague in relation to the question of Parasitism,” _ibid._, Nov., 1876.--_Idem_, “Description of the new Equine Fluke (_Gastrodiscus Sonsinoii_),” _ibid._, April, 1877.--_Idem_, “On Worm-like Organisms within the Mitral Valve of a Horse,” _ibid._, 1877.--_Idem_, “Entozoa of the Horse and Elephant” (see Bibl. No. 51).--_Idem_, “Observations respecting the Large-mouthed Maw-worm of the Horse,” ‘Veterinarian,’ Jan., 1877.--_Couchman, T._, “Worms in the Kidney of a Colt,” ‘Veterinarian,’ p. 145, 1857.--_Coupe, W._, “Fatal Parasitism in a Colt,” ‘Veterinarian,’ Dec., 1876, p. 844.--_Davaine_, “Les Cestoides,” in ‘Dict. Encycl. des Sci. Méd.,’ p. 591.--_Dick_ (see Knox).--_Dickens, C._, “Joint-lameness in Colts, associated with and symptomatic of Lumbricoid Worms,” ‘Veterinarian,’ p. 601, 1863.--_Dun, R._, “Remarks on Entozoa of the Horse,” ‘Veterinarian,’ 1854, p. 445.--_Dupuy_ (with M. Prince), “Filariæ in the Great Mesenteric of a Horse,” ‘Veterinarian,’ 1835, p. 570.--_Emmerson, C._, “Prevalence of Entozoa among Horses in the Island of Singapore,” ‘Veterinarian,’ 1861, p. 514.--_Friedberger, F._, ‘Die Kolik der Pferde,’ Berlin, 1874. (Reviewed by me in the ‘Veterinarian,’ Jan.-April, 1874.)--_Fry_, “Case of Worms in the Horse,” ‘The Hippiatrist,’ &c., vol. iii, p. 10, 1830.--_Gamgee, J._ (senior), “On Bots,” ‘Edin. Vet. Rev.,’ July, 1858.--_Goodworth, S._, “Obstruction of the Pyloric Orifice of the Stomach by Bots,” ‘Veterinarian,’ p. 410, 1837.--_Grellier, J._, “On the Worm in the Eye (of the Horse),” ‘Veterinarian,’ p. 18, 1844.--_Harlan, R._, “Case of a Colt killed by Worms,” in his ‘Med. and Phys. Researches,’ p. 554; see also ‘Med.-Chir. Rev.,’ 1836.--_Harris_, “A Case of Worms in the Arteries of a Colt,” ‘Veterinarian,’ p. 307, 1834.--_Harrison, J. D._, “The singular effect of Worms in the Stomach of a Mare,” ‘Veterinarian,’ p. 331, 1842.--_Hickman, T._, “Worm in the Eye of the Horse,” ‘Edin. Vet. Rev.,’ 1864, p. 653.--_Hopkinson, F._, “Account of a Worm in the Horse’s Eye,” from ‘Trans. of Amer. Phil. Soc.,’ in ‘Med. Comment.,’ vol. xi, p. 166, 1784.--_Hutchinson, J._, “Hydatid in the Eye of a Horse,” ‘Path. Soc. Trans.,’ and rep. in ‘Lancet,’ 1857.--_Huxley_, “On Echinococcus (from the Zebra),” see Bibl. No. 20, _o_.--_Jeaffreson, W._, “Case of Removal of a Worm from the Eye of an Arab Horse,” ‘Lancet,’ p. 690, 1836-37, and ‘Veterinarian,’ p. 471, 1837.--_Kennedy, M._, “Account of a Nondescript Worm (_Ascaris pellucidus_) found in the Eyes of Horses in India,” ‘Trans. Roy. Soc. Edin.,’ vol. xi, p. 107, 1816.--_Kirkman_, ‘Hydatids’ (see Bibl. No. 20, _o_).--_Knox_, ‘Edin. Med. and Surg. Journ.,’ 1836.--_Krabbe_ (l. c., in text).--_Lee, C. A._, “On _Filaria papillosa_ in the Anterior Chamber of the Eye of a Horse (and on Filariæ in general, &c.),” ‘Amer. Journ. Sci. and Art.,’ vol. xxxix, p. 278, 1840.--_Lessona, G._, “On the Bot (or Œstrus) of the Horse,” from ‘Recueil de Méd. Vét.,’ in ‘Veterinarian,’ p. 156, 1854.--_Leuckart_ (l. c., in text).--_Litt, W._, “A Singular Case (of an immense number of Worms in a Colt),” ‘Veterinarian,’ p. 529, 1852.--_Macnamara_, “On _F. papillosa_ in the Eye of Man and the Horse,” ‘Indian Ann. Med. Sci.,’ 1864.--_Marcet_ (see Bibl. No. 34).--_Mead, J._, “A Worm in the Scrotum of a Colt,” ‘Veterinarian,’ 1843, p. 648.--_Mégnin_, “Petit _Tænia inorme_ du Cheval,” in ‘Bull. de la Soc. Cent. de Méd. Vét.,’ t. vi, 3e série, p. 112.--_Idem_, ‘Monog. de la tribu des Sarcoptides,’ &c.; see also review by myself in the ‘Veterinarian,’ Aug., 1877.--_Mercer, J._, “On Entozoal or Worm-aneurism,” ‘Lond. Med. Gaz.,’ 1847, and in part x of “Contrib. to Zool. Path.,” in the ‘Veterinarian,’ p. 33, 1846.--_Meyrick, J._, “Death of a Colt from Entozoa within the Abdomen,” ‘Veterinarian,’ 1859, p. 695.--_Moir, J._, “Rupture of the Ileum resulting from Worms,” ‘Veterinarian,’ 1857, p. 265.--_Molyneux, R._, “On Worm in the Eye of Horses in India,” ‘Veterinarian,’ 1828, p. 309.--_Morgan, A._, “Case of Hydatid in the Brain of a Mare,” ‘Veterinarian,’ p. 396, 1855.--_Numan, A._, ‘Ueber die Bremsen Larven, im Magen der Pferde,’ 1837.--_Idem_, “Entozoon (_Monostoma settenii_) from the Eye of a Horse,” from ‘Tidschr. voor naturl. Geschied. en Physiol.,’ 1842, in ‘Med.-Chir. Rev.,’ 1842.--_Idem_ (for remarks on _Cysticercus fistularis_), ‘Over den veelkop blaasworm’ (l. c., Bibl. No. 49), p. 263.--_Peall, T._, “A Discourse on ‘Worms,’” at p. 37, in his ‘Observations, chiefly practical, on some of the more common Diseases of the Horse,’ pub. at Cork, 1814.--_Percivall, C._, “Worm in the Eye of the Horse (two cases),” ‘Veterinarian,’ p. 75, 1828.--_Percivall, J._, “A Case of Ascarides in the large Intestines of the Horse,” ‘Veterinarian,’ p. 358, 1829.--_Poulton, T. J._, “Large numbers of Parasites in the Intestines of a Mare,” ‘Veterinarian,’ 1866, p. 385.--_Seaman, J._, “Worms in the Blood-vessels of Horses and Colts,” ‘Edin. Vet. Rev.,’ 1864, p. 520.--_Simonds_, “On Disease of the Mesenteric Artery, produced by Strongyli,” ‘Path. Soc. Trans.,’ 1854.--_Skeavington, G._, “On Worm in the Eye of the Horse (three cases),” ‘Veterinarian,’ 1834, p. 196.--_Sonsino, P._, “On the Entozoa of the Horse in relation to the late Egyptian Equine Plague,” ‘Veterinarian,’ Feb. and March, 1877.--_Tyndal, J._, “Worms in the Intestines of a Mare,” ‘Veterinarian,’ 1843, p. 629.--_Twining, W._, “Obs. on the Filaria or Threadworm found in the Eyes of Horses in India,” ‘Calcutta Med. and Phys. Soc. Trans.,’ vol. i, p. 345, 1825; rep. in ‘Veterinarian,’ p. 114, 1828.--_Valenciennes_, “On the _Spiroptera megastoma_ of Gurlt,” abstract of a paper from Acad. Sci. of Paris, reported in ‘Lancet,’ 1843.--_Varnell_, “Remarks on Cases of Parasitic Disease in Horses,” ‘Veterinarian,’ p. 201, 1864.--_Veret_, “Perforation of the small Intestines by _Ascarides lumbricoides_ (in the Horse),” from ‘Rec. de Méd. Vét.,’ in ‘Veterinarian,’ p. 569, 1837.--_Vincent_, “Curious case of Incurable Lameness from Hydatids,” ‘Veterinarian,’ 1848, p. 674; see also p. 3, _ibid._--_Wallis_, “Note on the occurrence of (250) Lumbrici in a Horse,” ‘Veterinary Record,’ 1849, p. 300.--_Walters, R. G._, “Parasites in the Kidneys of a Mare,” ‘Veterinarian,’ 1866, p. 265.--_Woodger_, “Hydatid in the Brain of a Horse,” ‘Veterinarian,’ 1863, p. 75.--_Woods, J. S._, “Tetanus in a Mare, associated with the Larvæ of _Œstrus equi_ within the Stomach and Duodenum,” ‘Veterinarian,’ 1859, p. 693.--_Wright_, “Strongyli in the Scrotum of a Colt,” ‘Veterinary Record,’ 1849, p. 385.--_Youatt_, “Worms between the Tunics of the Stomach,” ‘Veterinarian,’ 1835, p. 571.--_Idem_, “Tetanus, Worms in the Trachea, and Dilatation of the Heart, in a Zebra,” _ibid._, p. 504, 1836.--_Idem_, “Worms in the Nasal Cavity of the Horse,” _ibid._, p. 329, 1832.--_Zangger_, “Remarks on Entozoa,” from the French, ‘Veterinarian,’ 1855, p. 463.