AN AMICRONUCLEATE OXYTRICHA 499 



four lines of subcultures, lA, 2A, and 3A. These subcultures 

 were carried with daily isolations until December 26th. On this 

 date two new subcultures, C2 and C3, of four lines each were 

 begun from three cannibals isolated from five-day-old stock 

 cultures of 2A and 3A, respectively. On December 31st two 

 cultures, CI and CNl, of four lines each were added. The 

 ancestors of these cultures were a cannibal and a non-cannibal, 

 respectively, isolated on the preceding day from a six-day-old 

 stock culture of subculture lA. As the curves, averaged for 

 five-day periods, showing the division rates of the non-cannibal 

 subcultures (lA, 2A, and 3A) and of the cannibal subcultures 

 (CI, C2, and C3) were essentially identical in each set, they 

 have been combined in figure 2. The curve shows that the 

 division rate of non-cannibal subcultures (lA, 2A, and 3A) was 

 highest during the first three five-day periods and that there 

 was a considerable drop in the division rate, i.e., from 2.4 divi- 

 sions to 1.4 divisions per day, during the next period, while the 

 average division rate for the cannibal subcultures was con- 

 siderably higher, i.e., 2.2 divisions. These cannibal subcul- 

 tures maintained a consistently higher division rate until Janu- 

 ary 20th to 25th, when it dropped below that of the non-can- 

 nibal subcultures for the first time. From this time on till the 

 end of the cultures the division rates are very similar. It 

 should be noted that 3 A and 2 A died out on February 18th and 

 February 23rd, respectively, whereas subcultures CI, C2, C3, 

 and 3 A lived until shortly after March 1st. Subcultures CNl 

 between January 10th and January 20th had a higher division 

 rate than any of the others, but this rapidly dropped until 

 February 9th, when the subculture died. 



The result of this experiment on cannibalism seemed plainly 

 to indicate that animals descended from cannibal ancestors 

 have a higher initial division rate as compared with animals 

 descended from non-cannibal ancestors. This experiment also 

 indicated the possibility, since their life in cultures was some- 

 what longer, that cannibal progeny are more hardy than prog- 

 eny of non-cannibal animals. 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 29, NO. 3 



