CROSS-INFECTION EXPERIMENTS 97 



Endolimax 



Chiang (1925) reports the presence of an amoeba similar to 

 E. nana of man in naturally infected rats. He names this amoeba 

 Endolimax ratti, basing his differentiation on the grounds that he 

 did not succeed in infecting rats with E. nana of man. Kessel 

 ( 1923a) failed to find natural infections of E. nana in rats although 

 he did find it in rats fed E. nana of man experimentally. Since the 

 flagellates of rats and their morphological characteristics are dis- 

 cussed at length by Dr. Wenrich in this monograph, they will not 

 be discussed in detail here. It seems apparent, however, that cer- 

 tain of the flagellates present in rats, e.g., T. muris, exhibit mor- 

 phological characteristics quite different from those found in man. 

 Others, however, are similar to protozoa found in man, e.g., T. 

 minuta is similar to the triflagellate Trichomonas of man (Faust, 

 1921), Giardia sijnoni (Lavier, 1924) similar to Giardia lamblia 

 and Chilomastix similar to Ghilomastix of man. 



The problem of procuring rats negative for protozoa is one 

 which is difficult. Brug (1919) mentions the irregularity with 

 which cysts of protozoa appear in the normally formed feces. 

 Examination of normal feces alone is considered tedious and un- 

 reliable. 



Kessel (1923) endeavored to establish a suitable method by ex- 

 amining rats, following the administration of large amounts of 

 magnesium sulphate. The rats were given no food for a period of 

 twenty-four hours and then fed bread soaked with a saturated 

 solution of Epsom saft. The rats which were negative for intestinal 

 amoeba when examined on three consecutive days, by this method 

 were also negative at autopsy when the intestine and cecum were 

 carefully examined for the parasites. This led the writer to feel 

 that he had a comparatively safe method of detection of rats nega- 

 tive for amoebae but not for curing rats of amoebic infection, as is 

 incorrectly stated by Wenyon (1926) and Knowles (1928). The 

 method, however, has not been thoroughly tested for the detection 

 of the intestinal flagellates of rats and should be repeated with 

 this objective in view. 



Chiang (1925) felt that giving an enema by means of a small 

 French catheter was a better method to employ. The writer has 

 used this methdd but because of the fact that the cecal valve of 

 the rat prevents the entrance of a catheter into the cecum and 

 thus makes it impossible to collect unemptied cecal material by 



