64 EFFECTS OF ADAPTATION sec. 



life prevails in the animal body. There nothing is indifferent, 

 nothing conld be otherwise than it is ; every organ, nay, every 

 cell and every part of a cell, is as it were tuned to the part 

 which it has to play in relation to the outer world. True, we 

 are not able to demonstrate all these adaptations in any one 

 species, but wherever we succeed in fathoming the significance 

 of a structural feature, it always turns out to be another adap- 

 tation, and any one who has ever attempted to study profoundly 

 the structure of any one species, and to give an account to 

 himself of the relation of its parts to the function of the 

 whole, wdll be much inclined to say with me, everything 

 depends on adaptation." Of course Weismann adds : " These 

 are convictions, I grant it, not absolutely proved facts." 



" If then," he continues, " the organism consists only of 

 adaptations based upon the constitution of its ancestors, it is 

 impossible to see what remains for any phyletic force to do, 

 even if it be conceived in the refined form of Nageli's idio- 

 plasm." 



Weismann then describes the whale in order to show the 

 completeness of adaptation, and concludes : " And now I 

 repeat my former question with regard to this special case. 

 If all that is characteristic in the animal depends on adapta- 

 tion, what is there left to represent the action of an internal 

 force of evolution ? " 



I also repudiate any special internal force of evolution. 

 According to my view, everything in evolution is due to 

 perfectly natural processes, to material, physical causes. 



I also have investigated the phenomena in question in 

 single forms of animals ; but I have arrived at a conclusion 

 which does not agree with AVeismann's — "that everything 

 depends on adaptation." 



But when Weismann says : Even where we cannot 

 recognise the purpose of a character at present, it will 

 ultimately prove to be adaptive, then I feel justified in re vers- 



