CONJUGATION IN PARAMECIUM 
299 
5. The differences in different races in the matter of conjuga- 
tion bear no simple relation to the relative size or other morpho- 
logical characteristics of the races. The two largest and the two 
smallest races observed conjugate only rarely; the race that con- 
jugates most frequently is intermediate in size. Among the 
races that conjugate but rarely are some with two micronuclei, 
some with but one. The race that conjugates most readily has 
two micronuclei. 
6 The fact that in a given race conjugation may be repeated 
(in the same line of descent) at intervals of but five days to a 
month, and the fact that races derived from a single individual 
may live without degeneration for three years without admixture 
from outside, tend, along with the results of Woodruff, Enriques, 
and others, to weaken the theory that conjugation is to be con- 
sidered the result of senile degeneration at the end of the life cycle. 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL 9, NO. 2. 
