74 THE SHORTER SCIENTIFIC PAPERS 



posed by the environment, and these together with the 

 rejnainder of the colony — the individual — perish. 



With a single exception, the available evidence is direct- 

 ly in accord with such a theory, although in general merely 

 demonstrating that amphimixis does not increase variabil- 

 ity (Warren, '99; Castell and Phillips, '03; Kellogg, '06; 

 Wright, Lee and Pearson, '07). The investigations of 

 Jennings, '11, on Paramecium seem to indicate that here 

 conjugation increases variability. The evidence, however, 

 was not altogether in harmony, in consequence of which 

 the subject was reserved for a future paper based upon 

 additional investigations. Even granting that such is the 

 case in Faramecium^, where conjugation consists of a tem- 

 porary union of gametes (conjugants) , it would not 

 necessarily follow that a similar condition would be found 

 in organisms where a total and permanent fusion of 

 gametes (copulants) occurred. 



While it would seem that such a theory as here outlined 

 is in advance of the earlier theories as to the cause of death 

 which are purely speculative, there is need of additional 

 data, and it is hoped that the several investigations now in 

 progress may throw additional light on the subject. 



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