THE FACTS AND FUNCTION OF SEX 25 



Whence do they come ; what is their precise relation 

 to the individual who bears them ? This question 

 and others connected with it logically precede any 

 discussion as to the meaning of the fact that these 

 gametes are of two kinds, male and female. It is 

 only in the latter half of this chapter that we shall 

 need to consider this matter. For the present we 

 can completely ignore this sexual dili'erence, and 

 need discuss neither the contrasting characters of 

 the two kinds of gamete, nor the mode of their 

 union, nor the function served by their differentia- 

 tion. These fascinating matters will be intelligible 

 only when we know exactly what the gamete is and 

 whence derived. 



The older fashion of expressing the facts — a 

 fashion perfectly just — was as follows. Consider 

 the single cell from which any of the higher animals 

 or plants is developed. (Later we shall see the orighi 

 of this cell.) It divides and divides and ultimately 

 forms a complete organism — a bird or a man or a 

 tree. But certain of the cells formed by these many 

 divisions have a special function. They are kept 

 apart in a particular portion of the organism ; and 

 they give rise to cells which do not serve the indi- 

 vidual, or, in a sense, form any part of its structure, 

 but which are ultimately shed and will give rise to 

 new individuals, after union with similar cells of the 

 opposite sex. 



This is a true account ; but the facts may be ex- 

 pressed in a much more significant fashion. I will 

 employ the words of Professor Arthur Thomson : — 



" From another point of view it may be said with 

 equal accuracy that the fertilised ovum [i.e. the 



