SCOPE OF GENETICS 



independently, but it misses the essential point. 

 For in each of these respects the individual is 

 double; and so to get a true picture of the 

 composition of the individual we have to think 

 how each of the two original gametes was pro- 

 vided in the matter of height, hair, colour, 

 mathematical ability, nail-shape, and the other 

 features that go to make the man we know. 

 The contribution of each gamete in each 

 respect has thus to be separately brought to 

 account. If we could make a list of all the 

 ingredients that go to form a man and could 

 set out how he is constituted in respect of 

 each of them, it Avould not suffice to give one 

 column of values for these ingredients, but 

 we must rule two columns, one for the ovum 

 and one for the spermatozoon, which united 

 in fertilisation to fonn that man, and in each 

 column we must represent how that gamete 

 was supplied in respect of each of the in- 

 gredients in our list. When the problem of 



