INHERITANCE IN HYDATINA 



79 



TABLE 38 



Showing number of fertilized eggs that hatched, out of 164 in lot {H2 from H), 



figure 1 



Percentage of viable eggs. 



56.0 



RESULTS OF THE EXPERIMENTS 



The results of the experiments may be stated under three 

 heads: (1) The effect of crossing on the viabiUty of eggs and on 

 the variabihty of the duration of the egg stage; (2) effect of 

 selection on viability of eggs in a hybrid Hne and in relatively 

 'pure' lines; and (3) inheritance of the sex-ratio. Figure 2 will 

 aid in presenting these results. 



1. The effect of crossing. Viability of eggs. This was tested 

 twice in the experiments: once in reciprocal crosses between lines 

 C and D, which were found, already distinctly different in via- 

 bility, in previous experiments, and again in reciprocals between 

 L2 and H'l, which had been made to differ in viability by means 

 of selection. In both cases the average viability of the two lots 

 of Fi fertilized eggs (for instance, C X D and D X C) was con- 

 siderably greater than the average viability of the inbred eggs 

 of the two lines crossed. In both casses, the two reciprocal 

 crosses were unequal, that one being most viable which had 

 the high viability mother, and conversely. These results indi- 

 cate that L2 and H2, made different by selection, differed from 

 one another in precisely the same way as did C and D, which 

 were found different in previous experiments. 



The inequality of the reciprocal crosses lasted, however, only 

 through the egg stage. For when parthenogenetic lines were 



