HEREDITY 



been repeatedly demonstrated by experiment. 

 Also poor nutrition of the mother may diminish 

 the number of eggs which she liberates, but will 

 not increase the proportion of males among the 

 offspring produced. 



An excellent summary of evidence on this 

 point was made by Cue'not in 1900. Attempts 

 to influence the sex of an embryo or larva by 

 altered nutrition of the embryo or larva itself 

 have proved equally futile. Practically the 

 only experimental evidence of value in favor 

 of this idea has been derived from the study 

 of insects, and this is capable of explanation 

 on quite different grounds from those which 

 first suggest themselves. It has sometimes been 

 observed, as by Mary Treat for example, that 

 a lot of insects poorly fed produce an excess 

 of males. In such lots, however, the mortality 

 is commonly high, and more females die than 

 males, because the female is usually larger and 

 requires more food to complete its development. 

 The fallacy in concluding from such evidence 

 that scanty nutrition causes individuals which 

 would otherwise become females to develop 

 into males was indicated years ago by Riley. 



158 



