DARWIN VS. GALIANI. 419 



adapted or is even dysteleological ; while, on the other hand, natural 

 and sexual selection has to account for most of what is adapted or what 

 is present for ornament's sake only, and which is therefore unexplain- 

 able by the simple laws of structure. So truly is this the correct view 

 of the case, that in fact the structure of organisms seems everywhere to 

 be a compromise between the requirements of the laws of structure 

 and the effects of natural selection, as we see — to employ an illustration 

 familiar to the physiologist — in the crossing of the air-passage by the 

 digestive passage in lung-breathing vertebrates, an arrangement full of 

 peril to life. On a previous occasion I showed that, in accounting for 

 this state of things, the Darwinian theory coincides, in its results, with 

 the optimism of Leibnitz. Still I am very far from overlooking the 

 difficulties which still remain on this point. One of the most serious 

 of these, in my opinion, is the power of regeneration, as it is called by 

 physiologists, and the nearly allied v?s medicatrix naturce, whether as 

 seen in the healing of wounds, in the circumscription and compensation 

 of internal morbid processes, or — at the outermost end of the series — 

 in the reproduction of a complete fresh-water polyp out of each of the 

 two halves into which one such polyp has been divided. This power 

 could not have been acquired through natural selection; and here it 

 seems inevitable for us to recognize laws of structure working toward 

 an end. But have we not a like phenomenon in the restoration of 

 mutilated crystals, a fact observed by Jordan, Lavalle, Pasteur, Senar- 

 mont, Scharff, and others ? So, too, the power which organisms possess 

 of perfecting themselves by practice appears to me not to have yet 

 been sufficiently studied with reference to natural selection. 



As a third argument against the theory of natural selection — one 

 which is supposed to negative all its claims to consideration — its op- 

 ponents always urge in the last place that in no single instance has 

 any one ever actually observed adaptive transformation of an organ by 

 inheritance and selection of the fittest forms. What transformations 

 have been thus effected in the past no man can tell, it is objected; and 

 inasmuch as, even in the future, observations and experiments on this 

 subject seem to be impracticable on many accounts, it is "claimed that 

 the doctrine of natural selection is not only an unproved hypothesis 

 now, but that it is fated for ever to remain so. Taking their stand 

 upon this ground, and contrasting themselves with the believers in 

 Darwinism, its opponents boast not a little that they are upholding the 

 standard of strict method, which requires us to accept as demonstrated 

 only what is proved by experiment or by mathematical reasoning. 



But this again is a mistake. If it is conceded that any one adapted 

 structure can be explained by natural selection, and if therefore this 

 theory is admitted to be legitimately deduced from legitimate premises, 

 then, in order to suppose the operation of natural selection, wherever 

 it is needed to explain phenomena, it is not necessary for us to actually 

 demonstrate such operation in the individual instance. It might be an 



