I gig] STOCT—IXTERSEXES 129 



processes of growth, development, and interaction of tissues, and 

 subject to modification or even complete determination by them. 



The older conception of mystical properties of maleness and 

 femaleness have given place to what are fundamentally meta- 

 bolic theories of sex determination. The principal points of dif- 

 ference in the large number of theories, thus to be grouped, lie in 

 questions regarding (i) time of determination, (2) whether the two 

 sexes are two contrasted conditions or simply phases of the same 

 general property, (3) to what extent sex development in the indi- 

 vidual is an evolution or an epigenesis, and (4) to what extent a 

 physical basis can be related to differences in the amount of chro- 

 matin present. 



To Darwin and many of his contemporaries the evolutionary 

 and adaptational significance of variations in sex were points of 

 principal interest. That such variations fundamentally involve 

 physiological processes operating in the organism was of course 

 recognized. The increased femaleness seen in females of certain 

 gynodioecious species was considered by Darwin as involving the 

 principle of compensation; with decreased expenditure of energy 

 in development of male organs there was a greater supply for 

 development and function of female organs. The doctrine of 

 conservation in expenditure for useless organs was likewise ap- 

 plied to the tendency to gynomonoecism as seen in such a species 

 as P. lanceolata (Ludwig 19); the stamens in the uppermost 

 flowers of a spike tend to be useless, and this was supposed 

 to induce their elimination. The tendency to poor development 

 of flowers at the tips of spikes, however, may be purely the result 

 of food supply being diverted for use of lower flowers, and as 

 such may be on quite a different physiological basis from the 

 condition that makes an individual only female. The intimate 

 association of many proterogynous flowers in a spike, however, 

 may well give opportunity for changes in metabolic processes 

 (Riddle) or influence of hormones (Lillie). 



A very interesting and suggestive conception which has fre- 

 quently been proposed is embodied in the view that maleness is a 

 "kataboUc habit'' of body (we may now add of an organ) induced 

 by preponderance of waste over repair, and that femaleness is an 



