364 THE INFLUENCE OF LIVING SUBKOTJNDINGS. 



spibe of his victoiy lie will not be able to derive the same 

 benefit from it as the weaker might have clone in the same cir- 

 cumstances. 



The capability of an animal for winning a suitable position 

 in life can never depend on one qualification alone, as for instance 

 the possession of powerful weapons. If we suppose that all the 

 Nauplius-larvaB of a Pachybdella were simultaneously produced, 

 and that they consequently all started simultaneously on a race 

 for their place on the abdomen of a crab, the victory would 

 naturally rest with the best swimmer. But the very organ 

 which had secured it this success would subsequently be of no 

 further use to it, since its powers of attachment and therewith 

 its final success in life depend on the clinging an tenure of the 

 larva. Supposing, then, that the individual arriving first were 

 ill-furnished in this respect, all the benefits of the victory would 

 be lost to it, since the crab might possibly be able, by a 

 vigorous movement of its hinder parts, to get rid of the unwel- 

 come guest. If the conquered laggart and inferior swimmer 

 were to arrive at this moment, and if it possessed better organs 

 for clinging than the foremost one, it might, though originally 

 beaten, finally become the possessor of the field — on the abdo- 

 men of the crab. 



Thus the selection effected by the issue of a direct combat 

 for any particular condition of existence can only lead to fvirther 

 results when the surviving party is also qualified to secure the 

 benefits of the victory. This point, as it seems to me, has not 

 seldom been lost sight of by Darwin's followers, and still more 

 by his opponents, who have frequently designated direct combat 

 as the only means of selection. Darwin himself, I am perfectly 

 convinced, never meant to say that a direct struggle between 

 two individuals was the only or even the most important means 

 of selection made vise of by nature in the process of natural 

 selection. Nevertheless, the struggle for existence cannot but 

 be rendered more severe by the occurrence of such personal 

 combat than it already is ; and since this will chiefly occur when 

 the individuals are as nearly alike as possible, it must, no doubt, 

 very frequently be a means brought into play by nature to 

 effect a selection between several varieties of the same species 



