308 Dynamic Theory. 



become lean, active and numerous as well as the other sex. If they 

 did they would have to mate with the slow and fat ones of that sex, and 

 in that case the lines between the sexes would have to be rearranged, be- 

 cause all the subsequently developed characters of femaleness, neces- 

 sarily follow the fat element, and if there is no antecedent force to dif- 

 ferentiate sexual distinctions, this alone would do it. But sex precedes 

 and consequent^ determines which shall be the more active party. At 

 the time of the first separation of a single cell into two halves, each of 

 which (as in the case of the Sagitta, ) may become the foundation of a 

 sexual gland, one male and the other female, we are to understand that 

 there has been a polar repulsion between the two pieces, just as if two 

 magnets had by some force external to themselves been turned so as to 

 present their positive poles towards each other. It is at this point that 

 the separation of the sexes takes place, and there is no doubt that the 

 process is gone through with in every sexual animal including man. In 

 every one, male or female, the asexual reproductive element, at an early 

 period of development, is split, and one half forms the beginning of 

 testes, and the other half the beginning of ovaries. ( As shown in chap. 

 3, however, the development of the former is subsequently suppressed 

 in the female, and the latter in the male. See page 24. ) 



The separation of the asexual cell into the two equal halves, then, is- 

 the beginning of sex differentiation. And here we meet with an ap- 

 parent paradox, because although we are constrained to affirm that these 

 moieties are equal, we yet find that they begin very soon to behave in a 

 different manner. But, again, remember the dextrose and levulose which 

 are chemically just alike but which are exactly opposite each other in 

 their reaction on a beam of light, one twisting it 81 to the right and 

 the other 81 to the left. (See chap. 27.) They are constructed like 

 two spiral stair-cases, one of which turns to the right and the other to 

 the left. So we can conceive of the primary sexual halves of an asexual 

 cell as being equal and yet reacting different^ from the same stimula- 

 tion. If a wire circuit canning a current of electricity be cut in two, 

 each of the severed ends will have a tension, one positive and the other 

 negative. In electrical engraving, explained in chap. 36, it is possible 

 to use either of these loose ends, but the negative end is better than the 

 positive. The negative current seems to be the more concentrated and 

 intense of the two, as if it were narrow while the other is wide. They 

 are both of equal speed and quantity, and are therefore regarded theoret- 

 ically as equal. When two polar bodies draw near to each other under 

 the influence of attraction, it is because one is 'positive and the other 

 negative, that is, one is pushed along on a positive and the other on a 

 negative current. Now if in the case of our primary sex cells the nega- 

 tive current is in any degree more intense than the other, the negative 



