1909.] CONKLIN— THE WORLD'S DEBT TO DARWIN. K 



dard of fitness until such exquisite adaptations as are found, for 

 example, in the case of the eye might be reached ; many persons 

 now doubt the omnipotence of selection, but if to natural selection 

 there be added some such factors as orthogenesis or mutations most 

 of the inherited adaptedness of animals and plants may be so ex- 

 plained. This seems to me to be the crowning feature of Darwin's 

 great theory; it is not so much its species- forming power which 

 impresses me as its ability to explain on simple and natural prin- 

 ciples very many of the wonderful adaptations of the living world. 

 On the other hand it must be admitted that there is one entire 

 class of adaptations which natural selection, as held by Darwin, is 

 unable to explain. Neither Darwinism, Lamarckism, nor any other 

 mechanical explanation hitherto proposed is able to explain satis- 

 factorily all the equally wonderful acquired, individual, or somatic 

 adaptations of organisms. All scientific theories of evolution hold 

 that racial adaptations are due to experience ; Lamarkism, that they 

 are the directly inherited effects of individual experience ; Darwin- 

 ism, that they are the indirect results of experience, through the 

 presentation of many variants to the action of selection and the sur- 

 vival of the best adapted. Neither of these theories could explain 

 sudden adaptations to conditions never experienced before; and 

 yet some individual adaptations are apparently of this sort. Bear 

 with me while I mention some of these cases which have been held 

 by several recent writers to be fatal to Darwinism. It has been 

 found that if the lens of the eye of a newt is removed it will be 

 regenerated perfectly within a few weeks. Now it may be assumed 

 that such an injury as this, involving as it does a very delicate sur- 

 gical operation, never took place in nature, and yet pure Darwinism 

 can explain this regeneration only by the supposition that the loss of 

 the lens has taken place so frequently among the ancestors of present 

 newts that they are perfectly adapted to this injury. Again the 

 eggs, embryos or adults of many animals may be cut or broken into 

 fragments or otherwise injured in such ways as could never have 

 occurred in nature, and yet these fragments will in many cases give 

 rise to perfect animals, "as if the pattern of the whole existed in 

 every part." This power of regeneration cannot be the result of 

 past experience, since there is no constant relation between it and 



