NURTURAL INFLUENCES 503 



it were, corroborate the bias of the ovum, for the percentage of 

 female offspring is higher when both parents are fed with lecithin. 

 It is not possible to follow the ova and prove that a relatively 

 anabolic one always becomes a female, and never a male, and so 

 on, but the argument from altered proportions seems sound. 

 While the lecithin treatment is followed by an increase in the 

 number of ova of " an anabolic type, rich in lecithin globules," 

 it often happens that the first litter after the beginning of the 

 treatment shows a marked preponderance of males. This Russo 

 regards as due to the fact that the injections stimulate the general 

 metabolism and inhibit the degeneration of the ova of the katabolic 

 type, capable of producing males. The increase in the number of 

 females occurs subsequently. 



It has been objected to Russo's experiments that one of the 

 two kinds of ova which he distinguishes are ova in the course 

 of degenerative change ; that he worked with families of selected 

 rabbits (for it is admitted that some females produce more 

 females than others, though this is not known to be a hereditary 

 character) ; that the high nutrition should result rather in more 

 offspring than in female offspring ; and that the number of 

 experiments did not afford a sufficient basis for the conclusion. 

 The experiments have been repeated by Basile and by Punnett, 

 but with entirely negative results. It is desirable that they 

 should be extended to larger numbers and to a variety of types. 



Several experimental investigations support the view that 

 changes in nutrition and other environmental conditions may 

 affect the mother so as to alter the ordinary proportions of the 

 sexes. Then Issakowitsch, working with the parthenogenetic 

 females of the Daphnid Simocephalits, von Malsen, working with 

 Dinophilus afialris, in which the ova are fertilised, found that 

 differences of temperature affected the proportion of the sexes, 

 apparently by affecting the nutrition of the mothers. Both 

 sets of experiments are the more satisfactory that they seem to 

 be free from any fallacy due to differential death-rate in the young 



