INADEQUACY OF NATURAL SELECTION, ETC. 647 



of skin-discrrrainativeness wliicli I contend is not thus accounted 

 for. But I deny that either the general sensitiveness or the 

 special sensitiveness results from natural selection ; and I have 

 years ao^o justified the first disbelief as I have recently the second. 

 In " The P'actors of Organic Evolution " [Essays^ 454 — 8), I 

 have given various reasons for inferring that the genesis of the 

 nervous system cannot be due to survival of the fittest ; but that 

 it is due to the direct eflfects of converse between the surface and 

 the environment ; and that thus only is to be explained the 

 strange fact that the nervous centres are originally superficial, and 

 migrate inwards during development. These conclusions I have, 

 in ihe essay Mr. Wallace criticizes, upheld by the evidence which 

 blind boys and skilled compositors furnish ; proving, as this does, 

 that increased nervous development is peripherally initiated. Mr. 

 Wallace's belief that skin-sensitiveness arose by natural selection, 

 is unsupported by a single fact. He assumes that it must have 

 been so produced because it is all-important to self-preservation. 

 My belief that it is directly initiated by converse with the environ- 

 ment, is supported by facts ; and I have given proof that the 

 assigned cause is now in operation. Am I called upon to abandon 

 my own supported belief and accept Mr. Wallace's unsupported 

 belief ? I think not. 



Referring to my argument concerning blind cave-animals, 

 Professor Lankester, in Nature of February 23, 1893, writes : — 



" Mr. Spencer shows that the saving of ponderable material in the sup- 

 pression of an eye is but a small economy : he loses sight of the fact, however, 

 that possibly, or even probably, the saving to the organism in the reduction 

 of an eye to a ludimentary state is not to be measured by mere bulk, but by 

 the non-expenditure of special materials and special activities which are con- 

 cerned in the production of an organ so peculiar and elaborate as is the verte- 

 brate eye.'' 



It seems to me that a supposition is here made to do duty as a 

 fact ; and that I might with equal propriety say that " possibly, 

 or even probably," the vertebrate eye is physiologically cheap : 

 its optical part, constituting nearly its whole bulk, consisting of 

 a low order of tissue. There is, indeed, strong reason for con- 

 sidering it physiologically cheap. If any one remembers how 

 relatively enormous are the eyes of a fish just out of the Q,gg — a 

 pair of eyes with a body and head attached ; and if he then 

 remembers that every aoig contains material for such a pair of 

 eyes ; he will see that eye-material constitutes a very considerable 

 part of the fish's roe ; and that, since the female fish provides 

 this quantity every year, it cannot be expensive. My argument 

 against Weismann is strengthened rather than weakened by con- 

 templation of these facts. 



Professor- Lankestor asks my attention to a hypothesis of his 

 43 



