126 PROTOZOAN PARASITISM 



sixth of probable validity and there may be others 

 of very small size not yet sufficiently identified. The 

 class has the common characteristic of possessing 

 flagella, comparatively long lash-like organelles con- 

 cerned with locomotion and food gathering. Their 

 bodies are variable in a common "pear" shape. 



Probably the majority of protozoologists most fa- 

 miliar with these organisms now believe the class 

 to be harmless to their hosts, although some hold the 

 question open. Among medical people there exists 

 the greatest confusion as to the different genera and 

 species and as to their effect on their hosts, a great 

 many practitioners believing that at least some of 

 them are disease producers. To these such terms as 

 ''flagellosis," flagellate infection, flagellate diarrhoea, 

 and flagellate dysentery, relate to clinical states of 

 more or less definiteness in their minds. 



In many medical laboratories the only names 

 known are "flagellate," Trichomonas, or ''Cercomo- 

 nas/' and the finding of such an organism in the stool 

 is sufficient evidence for the institution of treatment 

 of the conditions supposed to be due to it. The con- 

 fusion is so great that it is necessary to discount or 

 ignore the bulk of medical report on the subject. 



There exists no reason why any examiner may 

 not easily identify the common flagellates of the ali- 

 mentary tract of man. Trichomonas, Chilomastix, and 

 Giardia, although the very small ones, Emhadomonas, 

 Tricercomonas, and Enter oinonas, require consider- 

 able acuteness. 



