388 Experimental Zoology 



and little understood as the problems that they pretend to ex- 

 plain. If we inquire whether the greater katabolism or anabo- 

 lism of the male causes it to develop male or female produc- 

 ing spermatozoa, we shall find no definite answer to our question. 

 The idea is, however, expressed that the condition of the mother 

 determines the kind of egg she produces, — male or female, — 

 also that the effects of nutrition in the embryo itself determine its 

 sex, which is assumed to be formed at some early stage in the 

 embryonic or larval development. 



If the anabolic state is the one characteristic of the female, 

 how can she be supposed to produce male eggs, for however 

 much starved her tissues may become, she is not thereby changed 

 into a male, and until this occurred it is not clear why male eggs 

 should appear, unless the eggs are supposed to be more easily 

 affected than the formed tissues of the parent. But the most seri- 

 ous objections to the theory are the two following: Statistics 

 show that even under extremes of nourishment of the parent both 

 males and females appear, and if any difference of ratio is found, 

 it is so slight that one can only be surprised that the data give 

 such meager results in favor of the theory. If, on the other hand, 

 the determination of sex is supposed to be due to the nourish- 

 ment of the embryo, the best-ascertained facts, both experimental 

 and statistical, are diametrically opposed to the hypothesis. The 

 results show rather that differences in nourishment may cause 

 a greater mortality of one sex, or possibly that they favor the 

 development of one kind of egg rather than the other. There- 

 fore unless Geddes and Thomson can give their view, either a 

 clearer interpretation, or bring it into accord with the best- ascer- 

 tained facts, I do not think it can be looked upon as having in 

 any degree given even a proximate solution of the problem of the 

 determination of sex. 



LITERATURE, CHAPTER XXV ^ 



Andrews. Controlling of Sex in Butterflies. The Entomologist, VI. 



1873. 

 Bertillon. De I'influence de la primogeniture sur la sexualite. Bull. 



Soc. Anthrop. Paris, XI. 1876. 



