roxicm 



nxv(.i:.\ FOR PROT<>/.>\. 



457 



ickroaches (Periplaneta americana.') were obtained in Balti- 

 were all the parasitic protozoa in culture and most of 

 th<- free-living protozoa. The exact source of the frogs (Rana 

 pipicns), fish, salamanders and rats is not known. 



METHODS. 



Tin- protozoa-harboring animals and the protozoan cultir 

 wen- pla< r<l in tla-ks into which tank oxygen of <>7 per cent, purity 

 \\a- inn until the air was removed, or practically >o. Tin- tlasks 

 \\i-n- then clami)ed down securely and from I 17(10 mm. mm -nr\ > 

 -laiidard atmospheres (except for temperature correction i 

 \\ere a<lded to the I atmosphere at the time of the experiment. 

 ( Mher detail* of methods are given under the experiment* on thr 

 different animals. 



EXPERIMENTS. 



i. Termites. 



Tin oxygenation at various pressures on the pnu. 



oi loin termites is given in table I. The minimum time 



TABU I. 



* Xut killed in t 



rei|iiireil to kill the proto/oa of termite- an<l other animals \\a- 

 olitained as follow*: Se\ eral experiment* \\eic *taned at the *ame 

 inie so that an\ one could be stopped without interfering with 



