Further Studies on the Life History of Blepharisma Undulans.

Studies on the life history of Blepharisma undulans were carried on for just 6 years, all the animals employed being the progeny of a single individual isolated November, 1921. The work was planned to determine, in particular, the viability of this infusorian in the absence of fertilization, and the effects of fertilization on the rate of reproduction, in an attempt to broaden the results from our earlier studies on Paramecium aurelia 1 and Spathidium spathula. 2 A preliminary statement of the characteristics of this race of Blepharisma undulans was published in 1922, 3 and a summary of the chief experimental results was presented in 1927. 4

The present communication is to reiterate the results previously presented in the light of the final year of study of the culture.

In brief, the conclusions derived from Paramecium and Spathidium that these infusorians are capable of unlimited reproduction, under favorable environmental conditions, without recourse to fertilization, may now be extended to Blepharisma; and, furthermore, the conclusion that fertilization accelerates the division rate, as previously demonstrated in Uroleptus 5 and in Spathidium, 2 may now be extended to Blepharisma.

These studies have been aided by a grant from the Bache Fund of the National Academy of Sciences.