296 RESEARCH IN PROTOZOOLOGY 



are deprived of food and water for twenty-four hours prior to the 

 experiment. This has the double advantage of making the animal 

 eager to eat, and of thoroughly emptying the stomach and small 

 intestine. Oocysts are washed by centrifuging in water. It is neces- 

 sary that chemicals which may have been used to prevent putre- 

 faction be entirely removed. The supernatant water is poured off 

 and the oocysts are recentrifuged in a small quantity of sweet milk. 

 The supernatant milk may be discarded and the oocysts remain 

 concentrated in a few drops of milk. This material is offered to the 

 starved rat and is immediately consumed. Sixty minutes after the 

 ingestion of the oocysts, the rat is killed and the intestine is re- 

 moved. At various points segments of the small intestine will ap- 

 pear to be dilated and to have white contents. The intestine should 

 be opened at these points and smears made of the contents. Vari- 

 ous stages of excystation will be readily found. A small quantity 

 of fine powdered charcoal may be added to the milk-oocyst mix- 

 ture before it is administered, if it is desired to identify the experi- 

 mental food and to make a precise determination of the distance 

 the food has traveled in the intestine. This technique has been used 

 by Chapman (1929) in an attempt to obtain pure coccidia protein 

 for immunological purposes. 



PROBLEMS 



Treatment. Undoubtedly the most important problem relating to 

 coccidiosis is the treatment of it, particularly in domestic animals. 

 As far as is known, coccidiosis appears to be a very rare disease 

 of man, some two hundred cases having been reported to date. It 

 is possible, however, due to ignorance of the clinical manifes- 

 tations that many cases have been missed. Reasoning by analogy 

 from the behavior of the acute infections in young animals it might 

 be expected that the most severe symptoms and that death, if the 

 infection is ever fatal to man, would occur before thesexual phase 

 is well under way. Inasmuch as the present methods of diagnosis 

 are all based upon the recovery of the oocysts it is easy to see 

 that severe cases might go undiagnosed because of the absence of 

 oocysts in the feces at the time of examination, and the mild cases, 

 not requiring an examination of feces, might likewise go unrecog- 

 nized. Because of the paucity of cases in man, few therapeutic 

 measures have been attempted, and none have been established 

 as a specific treatment. 



