THEORY OF EVOLUTION 



183 



Paramecium at each division, the genetic com- 

 position of parent and offspring slionld he the 

 same. Whether pseudo-parthenogenesis that 

 Woo(h'uff' and Ki-dmann have found occurring 

 in Paramecium at intervals involves a redistri- 

 bution of the hereditary factors is not clear. 

 Jennings's evidence seems incompatil)le with 

 sucli a view. 



IMore recently one of Jennings's students, 

 INIiddleton, lias made a careful series of selec- 

 tion experiments with Stylonychia (fig. 90) in 

 wliicli he selected for lines sliowing more rapid 





Fk;. 90. Styloiiy<'lii;i showing division into two. (After 

 Stein.) 



