•7(i RESEARCH IN PROTOZOOLOGY 



resistance of the strain and the condition of the buccal cavity, 

 whether diseased or normal. 



Trichomonads have been described from the mouths of lower 

 animals by Hegner and Ratclifife (1927a, 1927^'). A species, named 

 by these investigators Trichomonas canlstomce, was reported from 

 twenty-two of twenty-three dogs examined. Since this report was 

 prepared the twenty-third dog and twenty-six other dogs examined 

 have all been found to be positive; thus 100 per cent infection 

 existed in these forty-nine dogs from Baltimore. Trichomonads 

 were obtained also from the mouths of two cats ; these have been 

 named Trichomonas fcHstonice (Hegner and Ratcliffe, 1927a). 

 Although these two types have been given specific names there 

 is a possibility that they may belong to one species and that 

 this species may be the same as T. buccalis in man. Culture 

 and cross-infection experiments are necessary to determine this 

 point. 



Trichomonas vaginalis. This flagellate has been reported most 

 frequently from vaginal mucus but has also been recorded from 

 the urinary tract of man. It appears to be present in from ten to 

 fifty per cent of adult women (Brumpt, 1913 ; Hegner, 1925) and 

 hence must find transmission comparatively easy. As no cyst stage 

 occurs in its life-cycle it must be transmitted in the trophozoite 

 condition. How T. vaginalis reaches the vagina is uncertain. Speci- 

 mens from the vagina may easily gain access to the urinogenital 

 tract of men during coitus. The vagina may become infected dur- 

 ing coitus but this has still to be proved. Contamination with 

 specimens from the intestine or during homosexual practices are 

 also possibilities (Dickinson and Pierson, 1926). It seems probable 

 that the incidence of infection among men is higher than reports 

 now available indicate. The exact distribution of these flagellates 

 in the various parts of the urinogenital tract is not known. 



The only lower animals in which vaginal trichomonads have 

 been reported are monkeys belonging to the species Macacus 

 rhesus. Hegner and Ratclifife (1927) have given the name Trichom- 

 onas macacovagince to this form, although further studies are 

 necessary to prove conclusively that it dififers from the trichomonad 

 that lives in the intestine of the monkey. The writer (Hegner, 

 1926) has been unable to find trichomonads in the vagina of a 

 number of domesticated animals that have been examined, includ- 

 ing 35 sows, 100 cows, 103 calves and 108 sheep. Attempts to 



