290 THE GER.M-PLASM 



cells of the first kind, derived from the father and mother respec- 

 tively, came together, a mixture of the characters of the two 

 parents would result ; and if two of the latter kind came into 

 connection, none of the special characteristics either of the father 

 or mother, would be recognisable in the child, which would only 

 possess such characters as are common to the two families. 



4. The Force of Heredity 



We have now seen that ' pseudo-monogonic " heredity is to be 

 explained in terms of the idioplasm as follows : — the dominating 

 group of idants from one parent — the mother, let us say — 

 passes over completely into the germ-cell of the offspring, and 

 there meets with a weaker group of idants from the father in 

 the process of amphimixis. Although not all, but only a large 

 number of the determinants in the maternal group of idants 

 predominate, a marked resemblance between the mother and 

 child will result. 



The fact that such cases as this occur at all. was taken above 

 as a proof that the combination of ids in the idants persists 

 during ontogeny, — i.e., from germ-cell to germ-cell, — and that 

 the idants often, or even generally, remain unchanged in the 

 reducing division. It naturally does not follow, however, that 

 precisely that combination of idants which predominated in the 

 ontogeny of the parent must remain unaltered in the germ-cell 

 of the offspring : it 7nay do so, and such cases will frequently 

 occur amongst the thousands of ova or still more numerous 

 sperm-cells which are produced by a single individual in the 

 course of its life. 



In some families it certainly appears as if the perfect type 

 (• Habitus ') of an ancestor had been transmitted with great con- 

 stancy to the children through a great number of generations, 

 and we must therefore assume that the dominant group of 

 idants in the ancestor reappears very frequently in the germ- 

 cells of the offspring. Thus the high forehead, widely-separated 

 eyes, and small mouth of the imperial family of the Caesars, 

 the large and peculiarly hooked nose of the Bourbons, and the 

 projecting lower lip of the Hapsburgs, can all be traced through 

 several generations. It is, however, difficult to say whether 

 such similarities are not accidental, or whether our recognition 

 of them is merely due to an incomplete knowledge of the facts, 

 onlv those descendants being taken into consideration in whom 



