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RESEARCH IN PROTOZOOLOGY 



aspirator bottle (Fig. 18, A) with an outlet near the bottom is 

 provided with a burette tip and glass stopcock (Fig. 18, B) on a 

 curved stem set into a rubber stopper, as indicated in Fig. 18. 

 The bottle is filled with water and is placed on a shelf in the 

 incubator so that the contents of the bottle can drop into the Petri 



dish. The stopcock is so reg- 

 ulated that the tip delivers a 

 drop of water every two or 

 three minutes. This compen- 

 sates amply for the evapora- 

 tion of the oocyst-containing 

 solution, and sporulation goes 

 on rapidly. The use of this 

 method has led to the quick- 

 est yield of the largest pro- 

 portion of ripe oocysts of 

 any method used in this 

 laboratory. 



Inoculation. "Inoculation" 

 is used here rather loosely to 

 indicate the introduction of 

 organisms capable of starting 

 an infection into the body of a susceptible host. 



Coccidia may be inoculated into animals by three general meth- 

 ods, namely, (i) feeding, (2) injection into the stomach, and (3) 

 by surgical manipulation. 



The first method is comparatively simple and suffices when it 

 is required to inoculate an animal without regard to the exact 

 amount or number of organisms introduced, or when it is desir- 

 able to avoid the use of an ansesthetic. The animal to be inoculated 

 should be deprived of food and drink for at least twenty- four 

 hours before the attempted inoculation. The oocysts should be 

 washed free of any irritating or unpalatable chemical with which 

 they may have been in contact, and they should be concentrated by 

 centrifugation into the smallest volume which is convenient to 

 handle. Rats and mice may be easily infected by placing them in 

 a cage with a watchglass containing the concentrated oocysts in 

 two or three drops of milk. Cats may be inoculated in a similar 

 manner by using a slightly larger quantity of milk. It is not always 

 easy to persuade rabbits and guinea-pigs to drink milk, but if the 



Fig. 18. — Apparatus for maintain- 

 ing moisture content of segmenting 

 oocysts at incubator temperature. For 

 explanation see text. 



