THE AGKICULT 



URAL JOURNAL. 



testinal tract in the course of the disease. 

 In a very large percentage of the cases 

 which have come under my notice within 

 the last five years an intense gastro- 

 enteritis has been present upon post 

 mortem examination of tlie alimentary 

 canal. So marked is this condition 

 often that one cannot help being re- 

 minded forcibly of the post mortem ap- 

 pearance of a case of arsenical or other 

 corrosive poisoning. That such a con- 

 dition should be attributed to the inges- 

 tion of any directly acting cause — such 

 as irritant food or direct microbic action 

 — is negatived by the fact that these 

 symptoms are frequent concomitants of 

 the disease produced artificially by means 

 of the hypodermic syringe. As this fact, 

 which I consider of grave importance, 

 seems wholly or in part to have been un- 

 noticed by nearly all the workers with 

 this disease, I wish it to be understood 

 that these observations apply to the dis- 

 ease as manifested in Natal. 



Such a condition, of course, does not 

 negative the theory that the naturally 

 produced disease may he contracted 

 through the stomach or intestines, but it 

 shows that the specific gastritis cannot 

 be due to the ingestion of any directly 

 acting cause 



The incidence of zymotic diseases upon 

 any particular organ or set of organs, is, of 

 course, well recognised ; one recalls the 

 nephritis of scarlatina, the endocarditis 

 of iheumati'sm, gastritis of rabies, and — 

 perhaps the most striking instance of the 

 selective affinity of disease for specific 

 local manifestation — the lesions of foot- 

 and-mouth disease 



The same obscure selectivness may ac- 

 count for the intestinal lesions of horse- 

 sickness, and furnish an analogy for the 

 presumption that such lesions may exist 

 independently of any cause acting loc- 

 ally upon the mucous-membrane of the 

 stomach or intestine 



That with the ingestion of dew the 

 organism gains an entry into the system 

 seems improbable, for the infective cause 

 indeed can be but seldom existant with 

 or upon the dew, and this is evident, in- 

 asmuch as dew must, as an everyday oc- 

 currence, be ingested hy animals turned 



out to graze. That such dew entangles 

 or j^recipitates the organism from a con- 

 siderable height is improbable, because' 

 dew formation takes place only from air- 

 strata in contact, or nearly in contact, 

 witli the earth. This theory of precipi- 

 tation from considerable altitudes seems 

 also to be negatived when one- considers 

 the freedom from horsesiekness experi- 

 enced during rain. 



The possibility of producing the dis- 

 ease through ingestion of infected ma- 

 terial is well demonstrated, though 

 Avhether such infection is possible in the 

 presence of a perfectly normal gastric- 

 membrane is still a matter for decision. 

 In this connection we should bear in 

 mind the instructive experiments made 

 of late years, shewing how insusceptible 

 animals can be made liable to certain 

 diseases by introducing the organism into 

 a stomach, the lining membrane of which 

 lias been rendered abnormal by the pre- 

 vious ingestion of lactic acid or other 

 agent producing a slight degree of gas- 

 tritis, or other abnormality. 



The absolutely normal condition of the 

 gastric membrane of the South African 

 horse can but rarely exist where parasitic 

 invasion of the alimentary canal is so uu- 

 versal. 



If the stomach Avere the only medium 

 by which the disease might be introduced 

 some colour might be lent to this theory, 

 but subcutaneous intravenous, and also 

 intra-tra cheat injections prove that the 

 Ingestive Theory cannot be considered as 

 the only theory at present tenable or cap- 

 able of satisfying all the difficulties of 

 this illusive disease. 



Post mortem evidence seems to point 

 to the fact that the stomach lesions pro- 

 duced by ingestion of infective matter 

 are more severe than those induced in the 

 natural course of the disease. In the 

 case of one animal having received 150 

 c.c. of virulent blood the reaction was so 

 great as to be described in the post mor- 

 tem report as "showing the most marked 

 inflammatory changes, patches denuded 

 of epithelium, and small erosions. The 

 colour, instead of showing the usual dark- 

 venous colour of gastritis, was of the 

 brightest cherry red." In the duodenum 



