ENDOMIXIS IN PARAMECIUM AURELIA. 



459 



solution, 1 and therefore this seemed to offer an opportunity to 

 study the effect of a medium radically different in composition 

 from those previously employed in these studies. Accordingly 

 subcultures designated Ami, Am2, Am^, AEmi, AEm2, Om and 

 Mm were started from A, AE, and M respectively, and bred 

 on this medium. The extent of these cultures and the time of 

 appearance of endomixis (E) in the two sets is shown in the 

 following table: 



This table shows that the malted milk medium did not change 

 at all the periodicity of endomixis in either the A or milk sub- 

 cultures, while it consistently brought it about earlier in the 

 AE and M milk series. The results from the AE and M cultures 

 are therefore in accord with the results obtained in Series II of 

 these experiments, while those with A and apparently differ. 

 However, the non-appearance of endomixis earlier in the Am 

 series is readily explained by the fact that the process was just 

 about to occur in the parent culture when the Am subcultures 

 were branched, as is shown by the fact that it appeared in A 

 during the following period. 



The experiments with malted milk are obviously not extensive 

 enough to give any details of the effect of long subjection to 

 this medium on endomictic periodicity, but they adequately 

 answer, it is believed, the purpose of the present study by again 

 indicating that the appearance of endomixis may be slightly 



1 Peebles, "Regeneration and Regulation in Paramecium caudatum," BIOL. 

 BULL., 1912. 



