8 PARASITIC AMCEBJE OF MAN. 



phology of the two parasites and the occurrence of 

 the pathogenic species only in cases of dysentery. 



Although up to this time several investigators 

 had endeavored to separate the parasitic amoebae of 

 man into species, either pathogenic or non-pathogenic, 

 it must be admitted that until Schaudinn's publica- 

 tion appeared in 1903 no clear description had been 

 given of specific differences in this class of organisms 

 as it is represented in man. The epoch-making paper 

 of Schaudinn gave the results of his work at Rovigno 

 where he pursued a long series of researches upon 

 these organisms. He clearly showed that there oc- 

 curred in man at least two species of amoeba differing 

 in their morphology, methods of reproduction, and 

 life cycle; one, a harmless commensal, occurring 

 both in health and in disease, the other, the cause of 

 a form of dysentery. He was able to follow the 

 entire life cycle of both these organisms and by ex- 

 periments upon himself showed that one was harmless 

 and that the other when swallowed during a certain 

 stage of development w r as capable of producing 

 dysentery. He suffered from two attacks of the 

 disease acquired in this manner and four years later 

 died as the result of an abscess of the sigmoid flexure, 

 in all probability produced by the pathogenic amoeba 

 with which he had infected himself. To the harmless 

 amoeba he gave the name (f Ent amoeba coli" while 



