ANOTHER WAY OF LOOKING AT THE FACTS 505 



cussion. As Prof. T. H. Morgan says : " Admitting that all 

 eggs and all sperms carry the material basis that can produce both 

 the male and female, the two conditions being mutually ex- 

 clusive when development occurs, the immediate problem of sex- 

 determination resolves itself into a study of the conditions that 

 in each species regulate the development of one or the other 

 sex. It seems not improbable that this regulation is different 

 in different species, and that, therefore, it is futile to search for 

 any principle of sex-determination that is universal for all species 

 with separate sexes ; for while the fundamental internal change 

 that stands for the male or the female condition may be the 

 same in all unisexual forms, the factor that determines which 

 of the alternative states is realised may be very different in 

 different species." 



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." We wish, 

 however, to look at the problem from another point of view. 



10. Another Way of Looking at the Facts 



In a recent able article on sex-determination, Prof. H. E. 

 Jordan writes : " The results of the newer investigations on 

 sex-determination seem, at least temporarily, to have brought 

 us back to the position of Geddes and Thomson, namely, that 

 femaleness is causally related to a dominating cell-anabolism, 

 and maleness to a relatively preponderant cell-katabolism. 

 This conclusion would seem to be the base from which future 

 investigations will start in the attempt to further elucidate the 

 fundamental mechanism of sex-differentiation." 



To this physiological view of sex, first expounded in The 

 Evolution of Sex in 1889, a brief reference must now be made, 



