116 SEX 



cases appear to us to favour the view that 

 the sex-difference is fundamentally physio- 

 logical. 



In conclusion, our view is that the difference 

 between an ovum-producer and a sperm- 

 producer is fundamentally a difference in the 

 balance of chemical changes, i. e. in the ratio 

 of anabolic and kataboiic processes, which 

 may, of course, have its structural expression 

 in the relation of nucleoplasm and cytoplasm. 

 Nor do we leave this difference in metabolism- 

 rhythm as a mere vague phrase, for we see its 

 analogue in the contrast between the ovum 

 and the spermatozoon, macrogamete and 

 microgamete, between the encysted and the 

 flagellate cell, between the plant and the 

 animal, and in many a familiar contrast all 

 through the series of Organisata. We adhere, 

 in short, to the thesis of The Evolution of 

 Sex that the sex-difference is but one expres- 

 sion of a fundamental alternative in variation, 

 to be seen throughout the world of life. But 

 we may add that the numerous and puzzling 

 minor variations, which, as we have above 

 seen, exist between species and species, may 

 be explained, not so much in terms of the 

 structural and the hereditary differentiations 

 which embryologists and Mendelians are wont 

 to look for or to assume, but rather in terms 

 of time-variations ; that is in acceleration or 

 retardation of the phases of life in adult or in 

 embryo, in sex-elements or in their initial 

 germ-cells, and in the interrelations of these. 



