302 HEREDITY IN THE PROTOZOA 



to each of the resulting paramecia. Four lines of 

 descent come from these four individuals from each 

 ex-conjugant. Do the four different lines show 

 differences, and do these differences bear any re- 

 lation to the differences that existed in the original 

 parents? In other words, are the two cell divisions, 

 in which the products of the three divisions of the 

 conjugated nuclei are sorted out, comparable, as 

 has been suggested, to the two maturation divisions 

 of the Metazoa? Calkins and Gregory have ob- 

 tained results with Paramecium caudatum indicat- 

 ing that the four lines derived from each ex-con- 

 jugant may show difTerent rates of division and 

 different frequencies of conjugation-periods. This 

 evidence see s at first sight to indicate that the 

 two cell-divisions following conjugation may produce 

 from the same material (conjugation nucleus) at 

 least four different lines. If these results do not 

 fall within the nornral range of fluctuating vari- 

 ability, then it m.ust be supposed that there occurs 

 some process of sorting out of the elements (genes?) 

 in the conjugated nucleus during its three con- 

 secutive divisions (in other words, segregation oc- 

 curs), or else that imperfections and irregularities in 

 the division either of the micronuclei or of the 

 cytoplasm are introduced at this time. If the latter 

 view were established one would expect that only 

 some of the new lines would have a survival value 

 if placed in competition. The remarkable fact that 

 many of these lines soon die out even with the best 

 attention, might possibly be appealed to as evidence 



