HOST-PARASITE RELATIONS I INTESTINAL PROTOZOA 



mens from the intestine, as suggested above, or during 

 homosexual practices are also possibilities (Dickinson 

 and Pier son, 1926). It seems probable that the incidence 

 of infection among men is higher than reports now avail- 

 able indicate. The exact distribution of these flagellates 

 in the various parts of the urinogenital tract is not 

 known. 



Host-parasite relations. The relations of T. vaginalis 

 to its host cannot be stated with certainty. It is reported 

 to be commonly present when the vaginal mucous mem- 

 brane is in an abnormal condition and when the reaction 

 of the vaginal mucus is acid. Treatment with sodium bi- 

 carbonate is therefore recommended by some physicians 

 so as to change the vaginal contents to an alkaline con- 

 dition. Whether the trichomonads are pathogenic and 

 bring about a diseased condition in the vagina or this 

 condition is favorable for the growth and multiplication 

 of the flagellates is a question not yet solved. 



Host-parasite specificity. So far as the writer is aware, 

 no trichomonads have been reported from the vagina of 

 lower animals. Blockmann (1884) and Dock (1894) 

 were unable to infect dogs, rabbits, and guinea-pigs with 

 specimens from man. Under the writer's direction, va- 

 ginal mucus from the following freshly slaughtered 

 animals has been examined with negative results: 35 

 sows, 100 cows, 103 calves, and 108 sheep. Recently the 

 writer has obtained trichomonads from the vagina of 

 several monkeys, Macactts rhesus, maintained in the De- 

 partment of Embryology of the Carnegie Institution of 

 Washington. These have been described as a new species, 



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