Darling has been so successful in his experimental work with kittens that he compares the colon of a kitten to a test tube and suggests the procedure of rectal injections of material containing amoebae as a means of differentiating the two human amoebae. On the other hand Walker was unable to infect kittens and monkeys with material containing pathogenic amoebae and he makes the statement that such failures would indicate the greater susceptibility of man to infection, as he was able to infect 17 out of 20 men with one feeding of such material. Sellards and Baetjer note that inoculation of kittens per rectum or by feeding dysenteric stools rich in amoebae has resulted in infection in about 50% of experiments. By inoculating the material directly into the caecum they were able to infect every one of their kittens. They were also able to propagate a strain of amoebae through a series of animals for several months. The intracaecal inoculations yielded positive results in diagnosis of human amoebiasis when the clinical manifestations were obscure and the amoebae in the discharges so few and atypical as to make such an examination unsatisfactory. _Other Intestinal Amoebae._—It is a remarkable fact that one of the most common of the intestinal amoebae, _Endolimax nana_, has only recently been reported (Wenyon and O’Conner in 1917). In the examination of the stools of American soldiers Kofoid found it present in 28% of his examinations while _E. coli_ was present in 23% of cases and _E. histolytica_ in 9.3%. In examining 156 British soldiers Dobell noted its presence in 33% of them. The general view is that it is not pathogenic but its great importance is in the possibility of its being mistaken in its cyst form for _E. histolytica_. The living amoeba averages about 8 microns but in stained specimens it is somewhat smaller. In freshly passed faeces the amoeboid motion is sluggish and the nucleus indistinct. This amoeba is best identified by haematoxylin stained specimens when the nucleus shows a measurement of about 2 microns with a large eccentric karyosome which exhibits a variety of form. Unless perfectly fresh material is stained the degenerative changes in the amoebae may give a signet ring appearance of karyosome and ring nucleus. Such an appearance may suggest the limax nucleus. The mature cysts are usually oval, but sometimes round, and contain 4 nuclei, but when newly formed may only have one nucleus. The nucleus is large in the uninucleate form (up to 3 microns) but in the quadrinucleate forms it is about 1.2 microns with a large eccentric mass of chromatin. Chromidial bodies are rarely, if ever, present in these cysts.