74 



SELECTION IN CLADOCERA ON THE BASIS OF 



reaction to lights that the only selection possible in very many cases 

 was from among individuals showing no reaction; and that in the 

 remaining cases the selections in the minus strains were postively 

 reacting individuals with the highest reaction-times. 



Lines 740 and 757 were subjected to selection from August and 

 November 1912 to May 1917. Lines 794, 795, and 796 were used in 

 selection from December 1914 to May 1917. All these lines of S. 

 expinosus, except Line 757, originated from mothers obtained from 

 Pond IV, the larger surface-water pond on the hill, a mile from the 

 laboratory of the Station for Experimental Evolution. 



Table 33. — Selection summary for Line 794- 



Table 34. — Same-day broods. Summary of data for Line 794- 



Line 794. 



The selection data for Line 794 are given in tables 33 and 34 

 and figure 11. 



This line and Lines 795 and 79G originated from three mothers 

 collected December 11, 1914. Selection was begun with the first 



