HOST-PARASITE RELATIONS I INTESTINAL PROTOZOA 



cysts from man. Six of the eight kittens suffered from 

 diarrhea and died in from one to eight weeks, and 6 of 

 the 9 mice became infected, but their symptoms were not 

 so severe. Surprising resuhs were later obtained by Por- 

 ter (1919), who induced diarrhea in rats by feeding 

 them on a supply of drinking water containing cysts ; and 

 infected rats on cysts that had passed through the diges- 

 tive tract of flies and cockroaches. Deschiens (1921) was 

 also surprisingly successful in his cross-infection experi- 

 ments. Four cats, 2 of which were fed cysts of G. muris 

 and the other 2 cysts of G. lamblia, became infected, 

 developed dysentery and three of them died. Infection 

 followed by symptoms was induced in 2 cats by the intra- 

 rectal injection of trophozoites of G. muris. Four of 5 

 mice fed on cysts of G. lamhlia became infected and died ; 

 whereas 5 mice that were already infected with G. muris 

 suffered no ill effects from similar feedings. Cysts of 

 G. muris from a cat infected with this species brought 

 about a fatal infection in 4 of 5 clean mice, whereas 5 

 mice already infected with G. muris suffered no ill results. 

 These results have not yet been confirmed. Simon ( 1922) 

 on the contrary was unable to infect rats with human 

 giardia cysts. Five laboratory rats and 5 wild rats were 

 fed washed cysts but no diarrhea resulted and no giardias 

 were found at autopsy. He succeeded, however, in infect- 

 ing rats by feeding them the entrails of mice containing 

 G. muris. Negative results were also reported by Des- 

 chiens (1925b) when he attempted to infect 2 kittens 

 per OS with cysts from a lion. Wenyon (1926) likewise 

 failed to infect 4 kittens with giardia cysts from man. 



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