284 THE GERM-PLASM 



As far as we can at present gather from the facts, even 

 in those cases in which the resemblance is a close one, 

 the child always differs from the parent either as regards 

 individual characters, or, as is more frequently the case, 

 in undefinable slightly characteristic details, such as the length 

 of the limbs, colour of the hair or eyes, or the quantity of hair. 

 These parts cannot be said to resemble those of the other 

 parent, but they give the impression that the main direction 

 in which heredity has tended has been slightly changed in 

 an undefinable way. A daughter may resemble her mother, 

 for instance, so closely that she is universally said to be an 

 exact image of her mother ; and yet a close comparison will show 

 that the likeness is by no means an exact one, and although the 

 child may not display a single paternal character, there are 

 nevertheless a number of parts which respectively differ from 

 those of the mother. In the case of identical twins, there can 

 be no doubt that manv of the minor differences existinof 

 between them are due to differences in the germ-plasm, and not 

 to the diversity of external influences. The germ-plasm of both 

 parents, that is to say, has taken part in determining the differ- 

 ent parts of the child, although in the case of one parent this 

 determination is slight and little marked, and has caused a 

 slight deviation from the maternal characters rather than the 

 development of specifically paternal ones. 



If this view is correct, and the germ-plasm of one of the 

 parents alone never determines the formation of the child, it 

 becomes more obvious than ever that even when heredity tends 

 to follow in the direction of one of the parents in the greatest 

 possible degree, the mother and daughter can never resemble 

 one another so closelv as do identical twins. Owingr to the slight 

 influence of the germ-plasm of the father, the type of the 

 daughter deviates somewhat from that which would have been 

 produced from the maternal germ-plasm alone ; and similarly, 

 if the mother owes her nature to the predominance of the germ- 

 plasm of one parent, a slight deviation must have occurred 

 owing to the weaker influence of the other parent. But the 

 whole of the germ-plasm of do//i grandparents cannot possibly 

 have been contained in the maternal germ-cell from which the 

 daughter arose, for the reducing division causes the removal of 

 half the germ-plasm from the egg-cell before fertilisation takes 

 place. Even if the idants which materially determine the type 



