INHERITANCE IN HYDATINA 



61 



apparently unequal. While both lie between the extremes of 

 their parents, each is more like the line that furnished its female 

 parent. 



This inequality of the reciprocal crosses also appears in the 

 percentage of viable eggs. If the series be again arranged in 

 the same order as in figure 1, these percentages are 45.7, 51.5, 

 32.4 and 5.3, respectively. Of the two reciprocal crosses, the 

 one whose mother came from the high viability line had the 

 more viable eggs, and conversely. The apparent inequality of 

 the reciprocals is further tested in the experiments next to be 

 described. 



It should be mentioned here in passing that from one of the 

 eggs of lot D X C, that hatched on the third da}^ of hatching, a 

 parthenogenetic line was reared as in table 8. The percentage 

 of male-producers was 31.2. 



{C X D) X (C X D). Females of the parthenogenetic line 

 C X D were paired with males of the same line November 24 

 to 30, 1911. From 54 matings thus made, 904 eggs were secured. 

 These eggs were observed daily until December 20, by which 

 time 425, or 47.0 per cent, had hatched. Table 9 records the 

 complete data. The standard deviation of the duration of the 

 egg stage is found to be 2.30. It does not seem necessary to 



TABLE 8 

 Showing details of parthenogenetic line D X C, figure 1 



Percentage of cf 9 



31.2 



1 Remainder of family not recorded. 



