146 PROTOZOAN PARASITIS^NI 



isms for as long as seven days, but that a sandy 

 soil bed led to disappearance by culture after twelve 

 hours. He found the viability of the organism in 

 water to vary with dilution, such dilution as would 

 occur when a stool is w^ashed into a pond or stream 

 giving little or no opportunity for survival and trans- 

 mission of the organisms. This is an interesting 

 observation, since it has a direct bearing on the 

 means of transmission, commonly believed to be im- 

 portant. Others have found Trichovionas resistant 

 to water. The writer's experiments on the point 

 are contradictory and indicate an uncontrolled fac- 

 tor. At one time neither tap water or distilled water 

 effected Trichomonas hominis in a test tube in the 

 incubator for about three hours. At another time 

 tap water killed wuthin two hours. At still other 

 times, controls for cultures, in tap water, incubated 

 overnight, failed to survive, but a similar failure has 

 occurred in physiological saline solutions. The 

 vomitus and feces of flies fed on feces containing 

 Trichomonas hominis produced viable organisms at 

 various intervals between twenty minutes and six 

 hours after ingestion. Cockroaches were not found 

 to pass viable organisms after ingesting them. Tri- 

 chomonas hominis in feces w^as destroyed by 2% 

 carbolic acid in 5 minutes, 1% creolin in 5 minutes, 

 and 0.5% lysol in 5 minutes. 



Trichomonas hominis is a pearshaped flagellate 

 measuring from 5 to 15 microns in length. When 

 very active it darts about in quick motion, swimming 



