INTRA-SELECTIOX OR SELECTION AMONG TISSUES 241 



at first sight to be so. There is a whole range of facts which seem to 

 be intelligible only in terms of the Lamarckian theory ; in particular, 

 the existence of numberless vestigial or rudimentary organs which 

 have degenerated through disuse, the remains of eyes in animals which 

 live in darkness, of wings in running birds, of hind legs in swimming- 

 mammals (whales), and of ear muscles in Man, who no longer points 

 his ears, and so forth through a lonof list. 



According to Wiedersheim, there are in Man alone about two 

 hundred of these vestigial or rudimentary organs, and there is no 

 higher animal which does not possess some. In all, therefore, a piece 

 of the past history of the species is embodied in the actually existing 

 organism, and bears witness to the fact that much of what the 

 ancestors possessed is now supei'fluous, and is either transformed, 

 or is gradually set aside, or is still in process of being set aside. It 

 seems obvious that this gradual dwindling and degeneration of an 

 organ no longer needed cannot be explained through natural selection 

 in the Darwin- Wallace sense, for the process goes on so exceedingly 

 slowly that the minute differences in the size of an organ, which may 

 occur among individuals of the species at any given time during the 

 retrogressive process, cannot possibly have a selection value. Whether 

 the degenerate and now functionless hind leg of the whale is a little 

 larger or a little smaller can have no importance in the struggle for 

 existence ; the smaller organ cannot be considered either as a lesser 

 hindrance in swimming or as a greater economy of material, and the 

 case is the same in regard to most other instances of degeneration 

 through disuse. We therefore require another interpretation, and at 

 first sight this seems to be supplied by the Lamarckian principle. 



But the reverse process, the strengthening, the enlarging, and the 

 more perfect development of a part, very often goes on proportionately 

 to its more frequent use, and here again the Lamarckian principle 

 seems to afibrd a simple explanation. For we know that exercise 

 strengthens a part, as disuse weakens it, and if we could assume that 

 these results of use and disuse were transmitted from the individual 

 who brought them about or ' acquired ' them in the course of his life 

 to his offspring, then there would be nothing to object to in the 

 Lamarckian principle. But it is precisely here that the difficulty lies. 

 Can we assume such a transmission of ' acquired ' characters ? Does 

 it exist ? Can it be demonstrated ? 



That Lamarck did not even put this question to himself, but 



assumed such transmission as a matter of course, is readily intelligible 



when we consider the time at which he lived. He was himself one of 



the first to grasp the idea of the transmutation-hypothesis, and he 



I. Q 



