90 RESEARCH IN PROTOZOOLOGY 



in determining the presence of intestinal protozoa in man has 

 taught us that cysts and trophozoites do not appear at regular in- 

 tervals in the feces and has shown that repeated examination is 

 imperative in order to demonstrate infections. This same fact holds 

 true with the lower mammals. 



(b) Collection of feces following a purge. This method has been 

 found valuable in routine laboratory diagnosis for human protozoa. 

 It has been shown to hasten the diagnostic procedure and to insure 

 efficiency. Two types of purge may be given, one a mild laxative 

 which should be given on several consecutive days. This does not 

 often increase the number of stools per day but merely softens the 

 fecal matter. It will be found most valuable when it is impossible 

 to collect all stools passed. The other method is to examine stools 

 following the administration of a drastic purge. The stools by this 

 method are liquid and unless one can be assured that portions of 

 all stools will be collected for examination there is the possibility 

 that light positive infections will be missed because the protozoa 

 if present only in a few small areas may be flushed out in an unex- 

 amined portion of the stool. When animals are kept in individual 

 cages of such construction that all feces passed can be collected 

 in trays underneath the cages this method is valuable. The writer 

 has employed it successfully with rats, monkeys, kittens, and 

 dogs. 



(c) Collection of material by enema. This method is suitable 

 for some animals but does not appear to yield satisfactory results 

 in others. In animals with a large cecum, e.g., the pig, or with the 

 cecum almost entirely closed off by the cecal valve, e.g., the rat, 

 it is not as satisfactory a method as with those animals that do 

 not exhibit a pocket type of cecum. It is obvious that the enema 

 method is of value in detecting positive fecal material in the colon 

 only, since little or no material will be obtained from the cecum by 

 this method. 



(d) Collection directly from cecum by surgical method. Rat- 

 cliffe (1928) has collected cecal contents directly from the cecum 

 by operation for his bacterial and protozoal counts in diet experi- 

 ments. This method also lends possibilities for use in the detection 

 of protozoan negative animals but quite evidently requires further 

 careful observation on this point before it can be used with safety. 

 It is possible that the collection of material from a single isolated 

 region is not sufficiently representative of the whole colon and 



