ENDOMIXIS IN PARAMAECIUM AURELIA 



45 



from room temperature at approximately 20° to a thermostat at 

 29° to 30°. 



Experiment 12 (figs. XII, Xlla and b) 



In this experiment line XII was carried with infrequent slide changes 

 from 3/11 until its death on 6/17. On 4/5 lines Xlla and b were 

 branched off and carried with infrequent changes of slide until 5/5 

 when a rise of 3°-4° killed line Xlla, Xllb being ended at the same time. 

 The accompanying graphs show that endomixis occurred on the aver- 



_ _-Cj« \-JlH 



fi 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r 1 1 1 1 1 1 1 1 1 1 1 1 I'i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 n 1 1 iYi iiiiiiMiiiiii iri 



age once in every twenty-one generations in lines Xlla and b, while 

 in the parent line XII, it occurred once in twenty-six generations, a 

 decrease of five generations in favor of the former lines. 



Experiment 13 (figs. XIII and Xllla) 



In this experiment line XIII was branched off from line IV on 5/19 

 and carried through seventy-nine (eighty) generations 13 ' u with daily 

 slide changes until 6/11 without the occurrence of endomixis. On 

 5/25 line Xllla was branched off and carried, with daily slide changes, 

 until its death on 5/28, endomixis ensuing on 5/26 four generations 

 after the transfer to the higher temperature occurred. 



13 On 6/7 when the slide was changed only three cells were present and as it 

 was impossible to tell which of these belonged to the first and which to the 

 second generation of daughter cells, the total count is uncertain to the extent of 

 one generation. 



14 Reckoning from the last endomixis in line IV. 



