712 JOHN BEARD, 



I. Theses concerning Sex, Herniapliroditism, and Parthenogenesis. 



Here, I would lay down certain theses, concerning sex, herm- 

 aphroditism, and parthenogenesis. 



1. The male gamete, the spermatozoon, has and can have absolutely 

 no influence in determining the sex of the "ofifspring". Its rôle is 

 simply to bring about the effects due to amphimixis. 



2. After development has commenced, the nutrition of the de- 

 veloping germ, or of the mother, if development be in utero, cannot 

 have the slightest effect on the sex. 



3. Once the egg is fertilised, nothing whatever can influence the 

 sex of its most obvious product, the embryo. 



4. Nor is the sex determined in the moment of fertilisation: on 

 the contrary, it is predetermined, in all probability from an epoch 

 shortly antecedent to the formation of the egg-mother-cell or oocyte, 

 which becomes an "egg" by giving off the polar bodies (Fig. 1, p. 750). 



5. The sex is a function of the egg itself. With a given egg 

 nothing whatever can alter the sex of the embryo, destined to arise 

 from it. 



Since in the human subject all the cells (oocytes), which later on 

 become the actual ova, are already present long before birth, it seems 

 to follow, that here the sex of each and everyone of the future 

 offspring is already predetermined, even before the birth of the parent 

 itself. Each oocyte in the ovary of a new-born child would, therefore, 

 already at that early period have the stamp of sex impressed upon it. 



6. There are two kinds of eggs: of these the one is destined to 

 give rise to a male form, the other to a female one. For shortness 

 and simplicity these may be spoken of respectively as "male-eggs" 

 and "female-eggs". 



7. The number of primary germ-cells is constant for the species, 

 but it varies in different forms. It is always a member of the 

 geometrical progression 2, 4, 8, 16, 32, 64, 128, 256 etc. It may be 

 the like number in both sexes, thus in the dog-fish, Scyllium canicula, 

 it is 128 for either sex; or, again, it may be unlike in the two sexes, 

 and then the number of primary germ- cells in the female may be 

 double that in the male, thus, in the smooth skate, Baja hatis, it is 

 255 for the male and 512 for the female. 



But in every instance the primary germ- cell, sacrificed to form 

 the embryo, must be deducted; and, therefore, the number comes to 

 be 2n— 1. Thus, it is 127 in the dogfish, S. canicula, 255 in the 



