CHAPTER VII 

 COPROZOIC PROTOZOA 



By 



Justin Andrews 



The Johns Hopkins University School of Hygiene and 

 Public Health 



INTRODUCTION 



The coprozoic protozoa are protozoan organisms which live 

 within discharged feces. ^ They are all free-living protozoa and 



^ While the author has accepted this general definition in conformity with 

 previous pubHcations it seems worth while to point out certain difficulties 

 with it. Etymologically, the definition is quite sound as the word "coprozoa" 

 is derived from two Greek words "kopros" and "zoon," meaning "dung" 

 and "animal" respectively. Thus any animal which lives in dung is, accord- 

 ing to the derivation of the word, quite properly called a coprozoon. Never- 

 theless the tendency amongst protozoologists, while defining the term as 

 above, is to refer to the group those organisms which have reached their 

 fecal habitat by traversing the intestine rather than by contamination of 

 the stool after it has been passed. There are certain exceptions to this 

 tendency in those cases where the forms in question have been obviously 

 introduced with the diluting fluid, but the fact that many species of very 

 common well-know^n protozoa can thrive in slightly diluted feces has been 

 either overlooked or ignored. As is indicated in the text, it is not known 

 how many species of free-living protozoa can live in fecal cultures but the 

 number must surely be legion. Of this large number of protozoa which 

 are potentially capable of the coprozoic habit, probably only a few are able 

 to reach the feces via the intestine, so that there is a well-marked physio- 

 logical difference, namely, the resistance of their cysts to intestinal enzymes, 

 between the coprozoa which were introduced to the intestinal contents by 

 ingestion and those which reached the intestinal discharges by contamination. 

 Whether this distinction merits redefinition of the word "coprozoa" — limit- 

 ing it, perhaps, to forms which appear in feces due to ingestion but which 

 are not capable of entozoic propagation, and reserving such an expression 

 as "fecal contaminants" for those forms which thrive in feces after dis- 

 charges but which cannot survive passage through the intestine and, there- 

 fore, must be accidentally introduced thereafter— or whether these two 



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