Summary

• 1.  Fifty postnatal volunteers (25 with and 25 without T. vaginalis) were each given 3 intravaginal inoculations of concentrates from 48–72 hour cultures of T. tenax (buccalis).
• 2.  Whereas no permanent infections were established, T. tenax survived for periods of 48 (5), 72 (1), 168 (1) and 432 (1) hours respectively. The 7 and 18 day survivals probably involved some multiplication.
• 3.  Three brief attempts at intravaginal establishment of T. tenax by inoculating directly from mouth to vagina were unsuccessful.
• 4.  The complete inability of T. hominis and T. tenax to establish lasting intravaginal infections, and the far greater capacity for intravaginal survival exhibited by T. tenax over that shown by T. hominis, again lead us to state that the mouth, intestine and genital tracts of man are infected with 3 separate and distinct species of Trichomonas.