314 CONTAGIOUS DISEASES. 



account of the diseased state of the intestinej also the dung is to 

 he regarded as infectious. 



" 4. Experiments showing that infection is produced hy co- 

 hahitation with a diseased animal, or by keeping healthy animals 

 in a place whence a diseased animal had been removed. 



" 5. Several experiments were made to see whether feeding 

 healthy animals on matter obtained from the diseased organs 

 (intestinal ulcers especially) produces the disease. The experi- 

 ment was always attended with success, if a lesion-abrasion 

 existed in the mucous membrane of the mouth or pharynx ; this 

 was usually the case when the matter had to be introduced into 

 the mouth while the animal was being held by assistants. 



" There were, however, two cases which appear to prove that 

 the disease cannot be produced by simple feeding. 



" This was unfortunately at a time when I was not as yet 

 acquainted with the fact that in many animals the disease is of 

 so mild a form that it can hardly be recognised in the living 

 animal. I have not made any ]post mortem examination of those 

 two animals. 



" But since then I have made two other experiments, in which 

 the virus was brought directly into the stomach, by means of 

 an india-rubber tube introduced per fauces and oesophagus. In 

 both these instances the animals became diseased, and their 

 intestines were most conspicuously affected. 



" From the last three series of experiments, we may conclude 

 that the principal way in which contagion of pneumo-enteritis 

 is carried out, is through the instrumentality of the air and 

 the food. 



" 6. This series comprises experiments to prove that the virus 

 can be cultivated artificially — i.e., outside the body of an animal ; 

 in the case of splenic fever it has been successfully done by 

 Dr. Koch. 



" The experiments are seven in number : — (a.) Two refer to 

 cultivations commenced with fluid peritoneal exudation ; (5.) In 

 the five others the virus had been obtained by cultivation of 

 dried lymph from the peritoneum of an animal suffering from 

 the disease. 



" (a.) The cultivation of the virus for the first two cases was 

 carried out thus : — 



" Fluid peritoneal exudation of a diseased animal had been 



