Origin of Sex. 313 



The nuclear elements of the male and female cells are undoubtedly 

 complemental and equal in their essential functions as they are in ap- 

 parent size. The difference of bulk between the two is in the proto- 

 plasm surrounding the nuclei. It is probable that the protoplasm of 

 the male cell is more differentiated and more animal, while that of the 

 female cell is less differentiated, more vegetative and more bulky. Why 

 one cell should have remained passive, quiscent and bulky, while the 

 other became active, mobile and unhampered, can be accounted for on 

 principles of physiological economy. If both cells were passive they 

 might never come within the sphere of each others influence or get to- 

 gether at all. If both were active they might fly around and still miss 

 each other. The easiest person to find is one who is always in the same 

 habitual place. But as I have shown above, the differentiation which 

 creates sex in the first place, puts upon the male cell a little more activ- 

 ity of movement, which by differentiating its protoplasm would tend to 

 increase its mobility. And this masculine activity would make unneces- 

 sary, and by so much discourage, activity on the part of the female cell, 

 and so render it more quiescent and in better condition to conserve a 

 store of provisions. But the passivity of the ovum is not to be unduly 

 exaggerated. In the mammals at the proper moment it is liberated 

 from the ovary and travels down the fallopian tube into the uterus, in 

 which place, or on its way thither, it may be met by the spermatozoon 

 which has traveled a somewhat greater distance to meet it. The union 

 of these two into a single cell, and the subsequent segmentation of this 

 cell, and the development of the embryo, are described in chap. 3, 

 [ Embryology ]. The protoplasm accompanying the two cells is mingled 

 to form a common supply for the immediate growth of the embryo. The 

 mechanical advantage and necessity of the greater bulk of this raw 

 material remaining with the more conservative ovum, and the more dif- 

 ferentiated and mobile part with the more active spermatozoon, are ob- 

 vious. As remarked above, the inequalities of se, both in the primary 

 sex cells and in the subsequent development of the individuals, have 

 arisen from external causes and are not in the essence of sex. It has 

 been shown elsewhere how parasitism tends to the reduction of the 

 powers and activities of the individual. Among the true parasities the 

 female is usually larger than the male. This difference is in the parts 

 concerned in reproduction, especially the ovaries, ovisac, &c. The 

 female being the nurse of the embryos, she becomes the receptacle and 

 depository of the food ; but as this food is absorbed from the host she 

 lives upon, without effort to the parasite and is appropriated directly by 

 the embryos, the agency of the female is purely passive and negative, 

 and such "anabolism" as appears to accompany the process, belongs 

 rather to the impregnated ova and the growing embryos than to the 



