a1 From the Molteno Institute, Cambridge.
1. Three trichomonads have been cultivated and studied, T. hominis, Trichomonas sp. from M. nemestrinus (= R.T. strain), and T. batrachorum from English frogs and toads.
2. A number of strains of T. batrachorum were cultivated over periods varying from two weeks to five months without the appearance of a Eutrichomastix stage.
3. The division process of T. batrachorum has been studied. The new basal fibre arises as an outgrowth from the blepharoplast. The old axostyle is absorbed and new ones are formed from the daughter blepharoplast during the telophase. Six chromosomes appear during the prophase. Spindle fibres do not appear. There is a separation of the daughter blepharoplasts into centro-some and basal granule at the metaphase.
4. Division of T. hominis and Trichomonas sp. from M. nemestrinus is essentially similar to that of T. batrachorum. The number of chromosomes appeared to be five or six. Double individuals were found in the cultures, and in T. hominis individuals containing four or six sets of organellae. Their significance is obscure.
(Received November 25 1930)
Beit Memorial Research Fellow.