490 WATASE. [Vol. VI. 



The point which requires our special consideration is that 

 condition of the surroundings which determines the direction 

 along which the non-sexual embryo develops. Maupas' experi- 

 ments have shown conclusively that the variation of temperature 

 exercises a controlling influence upon the type of the develop- 

 ment of the non-sexual organism ; while the researches of Born 

 and Yung tend to show that the condition of nutrition has a 

 similar controlling influence. It is probable that several other 

 agencies may be able to bring about the same results in the 

 differentiation of sex as that produced by variation in nutrition 

 and temperature. For it seems probable, from what has been 

 said, that the influence of these two factors cannot be considered 

 in any other light than that of a stimulus, and the forces which 

 act as such a stimulus may not be restricted to the two already 

 mentioned. It is not easy to ascertain, however, the exact 

 potentiality of constitution whereby one and the same organism 

 which develops into a female under certain circumstances, is 

 at the same time capable of developing into a male organism 

 when placed in different surroundings. This is, nevertheless, 

 a fact, and it does not seem unreasonable, therefore, to con- 

 sider that that structure or quality which appears in the male 

 organism as distinctly masculine, becomes in the organism of 

 opposite sex the very attribute of what we consider as distinc- 

 tively feminine. According to this view, then, the two different 

 qualities which characterize the two organisms of opposite sexes 

 may be considered simply as two different phases of one and the 

 same substance, which are brought about under the influence of 

 different surroundings. 



Before concluding this paper there are a few points which 

 call for special remark : — 



(i) It is obvious, according to the present view, that because 

 two masses of the same kind of protoplasm react in two 

 different ways towards two different stimuli, each develops 

 respectively into a male and a female organism, and because 

 they develop into two different organisms, each assumes the 

 particular characteristics peculiar to each sex. This constitu- 

 tional peculiarity of two sexes extends down to the sexual cells. 

 The sexual differentiation of the organism does not exist, prop- 

 erly speaking, for the purpose of bringing together the two 

 germ-cells, as is frequently assumed by some naturalists, but 



