RELATIONS TO THE DISEASE. 531 



latter is on the whole of smaller size, its protoplasm is more 

 finely granular, and it does not appear to take up red 

 corpuscles, etc., as is the case with the former. The 

 distinction, however, can only be definitely drawn by the 

 result of experiment. Injection of certain quantities of 

 dysenteric stools containing the amoebae into various 

 animals per rectum has been carried out by different 

 observers, especially by Kruse and Pasquale. In cats, 

 in the majority of cases, a haemorrhagic enteritis is pro- 

 duced, amoebae being present in the stools and also in- 

 vading the mucous membrane of the intestine in the 

 ulcerated areas which are sometimes formed. The deep 

 infiltration of the submucous coat by the amoebae, which is 

 so characteristic a feature in the human disease, does not 

 occur in these animals. Not infrequently death follows. 

 Kruse and Pasquale obtained corresponding results when 

 the material from a liver abscess containing amoebae without 

 any other organisms was injected. In the absence of 

 cultures of amoebae outside the body, this evidence must 

 be taken as conclusive that the disease produced in cats 

 is really caused by the amoebae. Similar injections with 

 material containing amoebae derived from other sources are 

 unattended by any pathogenic effects of similar nature. 

 Feeding the animals with material containing the amoebae 

 is much more uncertain in its effect. Quincke and Roos 

 obtained no effects when the amoebae were administered, 

 but they obtained a fatal result in two out of four cases 

 when the cyst-like forms were given. From this fact they 

 infer that the latter are probably a cystic stage of the 

 former and that the former are destroyed in the gastric 

 contents. This practically constitutes the only important 

 evidence that a cystic stage of the organism has really 

 been observed. These observers found that the cyst-like 

 bodies were still present even after the material had been 

 kept for two or three weeks. 



From the above facts, all of which have received ample 

 confirmation, with the exception of the statements regarding 

 the cyst-like forms, there can be little or no doubt that the 



