1923] Kessel: Experimental Infection of Rats and Mice 419 



III. Effect on Cysts of Passage Through Digestive Tract 



During: this investigation the faecal material of the rats and mice 

 has been examined on a number of occasions twenty-four and forty- 

 eight hours after feeding the animals with human faecal material. 

 There is no constancy as to the appearance of normal or disintegrated 



TABLE 6 



Results Obtained prom Feeding Cysts of E. dtsenteriae, E. coli, and 



councilmania lafleuri, respectively, obtained erom infected 



Rats to Other Amoeba-Free Rats 



human amoebic cysts in the rat faeces. Cysts which are apparently 

 unmolested by the passage through the rodent have been recovered 

 while other cysts in different stages of disintegration have been 

 detected. In the examinations made 44 per cent contained no cysts 

 of any type, 40 per cent contained dead or degenerate cysts, and 

 16 per cent contained live cysts. This indicates a difference in 

 viability of the cysts. 



Two young amoeba-free rats and three young amoeba-free mice 

 were fed a mixture of barium sulphate, milk, and human faecal 



