[101] THE EVOLUTION OF THE FINS OF FISHES. 1081 



It thus becomes evident that Lamarck uever clearly recognized the 

 principle of natural selection which it has been the great merit of 

 Darwin and Wallace to discover and announce simultaneously, yet the 

 father of the doctrine of transmutation of species seems to have had 

 some sort of dim conception of the fact of the reality of a " struggle for 

 existence," as implied in his remarks on rivalry amongst males, and 

 when he implies that animals do thiugs the purpose of which is to gain 

 some advantage. 



The frequently quoted instance of the long neck of the Giraffe, which 

 Lamarck thought had been produced by the persistent efforts to feed 

 upon the foliage of trees by successive generations of the animal, has 

 made abundance of sport for superficial writers since his time. But let 

 us look into this matter a little more closely, and see if natural selection 

 is at all likely to have originated longer cervical vertebrte in this crea- 

 ture. Granting that the external conditions were such as to favor the 

 survival of loug-necked forms, the most that natural selection could do 

 would have been to preserve the long-necked individuals to reproduce 

 the species; it could originate no progressive morj^hological difleren- 

 tiation, but merely be the means of preventing the extinction of the 

 acquired increments of that differentiation. 



If Palceoutology is of any value as throwing any light upon the his- 

 tory of the evolution of the Giraffe, we probably have in Sivatherium^ 

 Bramatheriumj and Helladotherium forms which were antecedent in time. 

 The latter, especially, had a pretty long neck, and seems to have been 

 higher at the shoulders than at the rump, somewhat as in the Giraffe. 

 Here we have a probable stage of evolution of CamelopardaUs, or a sur- 

 vival of a form tending in that direction, but with a neck proportion- 

 ally no longer than Camehis, which is also allied. Now let us soberly 

 ask ourselves if it is likely that the effort to reach for herbage, if per- 

 sisted in on grassless plains, where the only food was the foliage of trees, 

 would not tend to cause the animal to lift its head and already long 

 neck, strengthen the ligamentum nuchae and cervical muscles, and in 

 pulling or wrenching off' this foliage stretch its neck more and more, 

 generation after generation, each of which would thus gain an inherited 

 advantage in obtaining food over the one which had preceded it in time. 

 Manifestly there must have been causes for this variation in one direc- 

 tion which would lead to an increased growth in length of the centrum 

 of each cervical vertebra. Variation would have had to constantly tend 

 in the one direction through a great many generations, which is in the 

 highest degree unlikely, if no adequate cause existed to determine that 

 direction. Darwin himself never lost sight of this difficulty, but his 

 followers have frequently expressed themselves as if variation itself and 

 natural selection were forces irrelative to the intrinsic forces exhibited 

 by living bodies ; for neither natural selection nor variation could pro- 

 duce any effects whatsoever if the environment were constantly the 

 tame about a living individualized entity without rivals, anymore than 



