82 A. FRANKLIN SHULL 



have been due to external conditions; at any rate, viability did 

 not increase when selection for low viability was discontinued. 

 Selection was then made for high and low viability in this ''ran- 

 dom" lot of eggs, but the results, as shown in L from L and 

 H from L, figure 2, show that selection was wholly ineffective. 

 The low viability eggs were permanently of low viability, not 

 kept low by continued selection; selection within the low via- 

 bility series was of no avail. 



In like manner, selection for high and low viability among 

 the high viability families of H3 (cf . Li from H, and Hi from H; 

 also, Lo from H, and H2 from H) did not alter the viability in the 

 direction of selection. The high viability eggs were inherently of 

 high viability, not maintained so by selection. 



3. Inheritance of the sex-ratio. In every case here recorded 

 in which two lines were crossed (for example, lines A and B 

 to produce D, also reciprocal crosses between C and D), the 

 cross was intermediate between the parent lines in the proportion 

 of male-producers. In the one case of reciprocal crosses recorded, 

 the reciprocals were unequal; each was nearer the line that furnished 

 the female parent. Unfortunately, only one of these reciprocals 

 was tested further, so it is not known whether this inequality 

 of the reciprocal crosses disappeared, as was the case with via- 

 bility, in the subsequent parthenogenetic lines. 



When a parthenogenetic line was inbred, the parthenogenetic 

 line derived from its fertilized eggs usually yielded about the 

 same proportion of male-producers as did the parent line. That 

 this was not necessarily the case, however, was shown when 

 two lines were reared from the same lot of inbred eggs. Thus, 

 in (C X D) X {C X D), the line bred from a low viability family 

 of eggs included 37 per cent of male-producers, while the line 

 from a high viability parent yielded only 20.5 per cent. This 

 was not due to the conceivable fact that one line was bred only 

 during a period of many male-producers, the other only during 

 a period of few male-producers; for when these two lines were 

 inbred, and their descendants inbred several times in succession, 

 the 37 per cent series maintained, with one exception, a propor- 

 tion of male-producers about 35 per cent (Li to L4), while the 



