ENTAMCEBA HISTOLYTICA 205 



(1903), who rediscovered the cysts, confirmed this observation, which was 

 repeated by Kuenen and Swellengrebel (1913), the writer and O'Connor 

 (1917), and Dobell (1917), and others. The infection in kittens is, as a 

 rule, of a very severe type, the whole of the surface of the large intestine 

 being infected with amoebae. The infection usually commences at the 

 lower part of the large intestine, and it is here that the changes in the 

 mucosa are most marked. Sellards and Leiva (1923a) have shown that 

 this is probably due to the natural stasis which occurs at this point. By 

 ligaturing the large intestine of cats at various levels and inoculating 

 infective material directly into the csecum they have demonstrated that 

 the infection commences and is most marked just above the ligature. 

 They see in this an explanation of the fact that in human beings amoebic 

 ulceration is most marked at the point where stasis occurs. If the animals 

 live long enough, definite ulcers occur as in human beings, but frequently 

 all the glands are infected over the whole gut wall and death results from 

 the general necrosis of the mucosa which is set up. Sellards and Leiva 

 (1923a) have shown that bacterial invasion of the blood also plays a 

 part, for they have cultivated various intestinal organisms from the 

 blood of infected cats. As a method of diagnosis of amoebic infection 

 in the cat they have employed a daily saline enema. The fluid is quickly 

 returned, and the flakes of blood-stained mucus which it carries with it 

 can be examined for amoebae. Infected cats frequently pass -per anum 

 a whitish fluid containing many broken-down cells and enormous numbers 

 of amoebae. In less acute cases the stools resemble those of amoebic 

 dysentery in man, there being faecal material containing masses of mucus 

 stained with dark red blood. Eecoyery rarely takes place in cats, and 

 when it does the infection dies out, there being no carrier condition 

 corresponding to that in human beings. The cysts of E. histolytica are 

 never formed in cats. As in man, secondary infection of the liver may 

 take place, leading to the formation of liver abscess, an observation 

 Avhich was first made by Marchoux (1899), and subsequently by Craig 

 (1905), Werner (1908), "^Huber (1909), the writer {I9l2d), Dale and 

 Dobell (1917), Mayer (1919), and Sellards and Leiva (1923ff). Harris 

 (1901) noted a similar condition in an experimentally infected dog. 



The infection in cats may be maintained indefinitely by injecting the 

 intestinal contents per rectum from one animal to another. The cats 

 must be only a few weeks old, as large, full-grown animals are more 

 resistant to infection. As the cysts of E. histolytica never occur in cats, 

 the infection cannot be handed on from cat to cat by feeding with intestinal 

 contents. The writer has never succeeded in infecting kittens by means 

 of material from liver abscess, in spite of the presence of active amoebae. 



Guinea-pigs have been infected by Baetjer and Sellards (1914), and 



