INHERITANCE IN HYDATINA 



69 



Effect, of selection for high viability in a hybrid line 



Let us now turn to the high viability series, beginning with 

 the parthenogenetic line in (C X D) X (C X D), whose parent 

 hatched 11 out of 15 eggs (viability 73.3 per cent). 



Hi. Females of the parthenogenetic line bred from a highly 

 viable family in {C X D) X (C X D) were paired with males of 

 the same line January 20 to 28, 1912. From 53 such matings, 

 728 fertilized eggs were obtained. By March .1, 381 of these, 

 or 52.3 per cent, had hatched (table 21). Of the low viability 

 lot of eggs, Lo, there hatched at the same time but 28.9 per cent. 



One of the above 53 females laid 16 eggs, of which 12, or 75 

 per cent, hatched. From the first of her twelve daughters the 

 parthenogenetic line designated Hj was reared. It included but 

 18.9 per cent of male-producers (table 22). 



Ho. Females of the parthenogenetic line Hi were paired with 

 males of the same line, February 17 to March 8, 1912. From 

 43 such females were obtained 583 eggs, of which 288, or 49.3 

 per cent, hatched before April 10 (table 23). The low viability 

 lot of eggs, La, corresponding to the high viability lot H2, hatched 

 but 35.3 per cent. It should be noted that these two lots of 

 eggs were not on the whole hatching simultaneously. Whereas 

 the bulk of the eggs in L2 hatched at the end of February, the 

 lot H2 reached its maximum about March 20. This was unavoid- 

 able owing to the fact that the scarcity of male-producers in 



TABLE 22 

 Showing details of parthenogenetic line Hi, in figure 1 



Percentage of cf 9 



18.9 



1 Remainder of family not recorded. 



