534 LIFE : OUTLINES OF GENERAL BIOLOGY 



the proportions of the male-producing and female-producing germ- 

 cells, affecting either the number formed or the number that sur- 

 vive, and (2) that in other cases there is no hint of any such influence, 

 the facts pointing rather to the view that the sex of the future 

 offspring is not only predestined but predetermined at a very early 

 stage in the germ-cells. Looking back over the array of facts of 

 which we have given samples, we would say, with Dr. F. H. A. 

 Marshall, that they point to the conclusion that "the sex of the 

 future organism is determined in different cases by different factors 

 and at different stages of development — either in the unfertilised 

 gamete, or at the moment of fertilisation, or in the early embryo". 



A PHYSIOLOGICAL WAY OF LOOKING AT THE FACTS.— 



To the physiological view of sex, first expounded in The Evolution 

 of Sex in 1889, a brief reference must now be made, for we find 

 ourselves unable to get away from the conviction that there is no 

 sex-determinant or factor at all, in the morphological or in the 

 Mendelian sense, but that what settles the sex is a metabolism- 

 rhythm, a relation of nucleoplasm and cytoplasm, a relation between 

 anabolism and katabolism. 



All through the series of organisms — and of animals in particular 

 — from the active Infusorians and the passive Sporozoa, to feverish 

 Birds and sluggish Reptiles, we read alternatives or antitheses 

 between liberal expenditure of energy and a more conservative 

 habit of storing. This primarily depends on the ratio between dis- 

 ruptive (katabolic) processes and constructive (anabolic) processes, 

 and we regard the sexes as expressions of the same contrast within 

 a given species. 



According to this view, the deep constitutional difference between 

 the male and the female organism, which makes of the one a sperm- 

 producer and of the other an egg-producer, is due to an initial 

 difference in the balance of chemical changes. The female seems to 

 be relatively the more constructive, whence her greater capacity 

 for sacrifices in maternity; the male relatively the more disruptive, 

 whence his usually more vivid life, his explosive energies in action. 

 In short, the sexes express a fundamental difference in the rhythm 

 of metabolism. 



This initial diffeRncc not only leads to the primary functional 

 distinction between male and female, but it also determines, either 

 from the start, or after maleness and femaleness have been in part 

 established, what particular expression will be given to a whole 

 series of secondary characters — both structural and functional — 

 whether a masculine or a feminine expression. 



Many sets of facts lead one to conclude that each sex-cell has a 

 complete equipment of masculine and feminine characters, and it 

 may be that the liberating stimulus which calls the one set or the 



