Abstract
On December 7, 1913, conjugation occurred in a mass culture started from my pedigreed race of Paramácium aurelia 1 at the 4,102d generation, showing that this race is a conjugating race when the proper conditions for its consummation are realized. 2
Variations in the tendency to conjugate which are exhibited by pure races and lines of Paramácium have led Calkins to the view that herein lies the clue to the directly opposite results derived from his races and from mine. 3 “The race that I worked with in 1901 was a conjugating race which died out in the 742d generation. Woodruff's long line of over 3,500 generations is a non-conjugating race and the two races cannot be compared in regard to vitality, since normal conjugation was prevented in the conjugating race, whereas in the non-conjugating race there was no artificial prevention of a normal process.” 4
Since conjugation has now occurred in animals from my race there is no evidence extant that a “non-conjugating” race of Paramácium exists.
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