HOST-PARASITE RELATIONS: INTESTINAL PROTOZOA 



enough to convict it of being pathogenic. The diarrheic 

 or pathogenic condition may have rendered the intesti- 

 nal contents particularly favorable for the growth and 

 reproduction of the flagellate and the presence of the red- 

 blood cells in the intestinal contents may have offered the 

 flagellates an opportunity to take them in along with 

 other kinds of food particles and does not prove that the 

 flagellates actually attack the host tissues. Furthermore, 

 cases of infection with Penatrichomonas that have never 

 exhibited evidence of diarrhea or dysentery have been 

 reported (Hegner, I925e). Kessel (1925a) has reported 

 the ingestion of red blood cells by the four-flagellated 

 trichomonad, Trichomonas hominis, found in the stool 

 of a patient suffering from bacillary dysentery and in 

 Trichomonas hominis (vaginalis^) from the urine of an- 

 other patient passed at the time of menstruation ; Reiche- 

 now (1925a) finds that in culture both the four-flagel- 

 lated and five-flagellated types will ingest red blood cells ; 

 and Wenyon (1926) states that he has observed them 

 in specimens passed by a patient suffering from bacil- 

 lary dysentery and in cultures containing rabbit blood. 

 It thus seems probable that all types of trichomonads may 

 under certain conditions take in erythrocytes. 



The relationship between the pentatrichomonads of 

 rat and man is a problem of considerable interest. 

 Wenrich and Yanoff (1927) go so far as to state that 

 the organisms from these two species of hosts belong 

 to the same species, and that the rat serves as a reser- 

 voir for the parasite of man. These authors also find 

 that infection in the rat with pentatrichomonads "is 

 usually accompanied by a great many leucocytes in the 



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