COPROZOIC PROTOZOA 6$ 



had been passed. It grew luxuriantly in diluted feces and in a 

 serum-saline medium. It was definitely proven not to be a con- 

 taminant. The relation of this organism to the individual from 

 which it was isolated is one of interesting speculation. 



The factors which influence excystation in these forms deserves 

 more study. The cysts are apparently resistant to intestinal 

 enzymes as they do not hatch within the body of the animal 

 through which they are passing yet they excyst readily in the 

 diluted discharges at room temperature. Dobell and O'Connor 

 (1921) have suggested the high temperature of the warm-blooded 

 vertebrates and the absence of free oxygen as possible conditions 

 which prevent coprozoic forms from multiplying within the intes- 

 tine. Possibly these same factors are concerned with the mech- 

 anism for excystation. These factors and many similar ones might 

 be studied profitably to explain the mode of excystation and the 

 general bionomics of the coprozoic protozoa. 



