INHERITANCE OF ACQUIRED CHARACTERS 199 



remarks: "Considering the width and depth of the effects 

 which the acceptance of one or the other of these hypotheses 

 must have on our views of life, the question, Which of them is 

 true? demands beyond all other questions whatever the atten- 

 tion of scientific men." 



Other illustrations of the supposed effect of use and disuse 

 are thus discussed by Dr. Edwin Grant Conklin: 



"In the first place, this whole line of argument starts with the 

 assumption that the individual habits of an animal are inherited, and 

 that these habits ultimately determine the structure, an assumption 

 which really begs the whole question ; for, after all, the substratum of 

 any habit must be some physical structure, and if modified habits are 

 inherited it must be because some modified structure is inherited. I 

 take an example which will serve as an illustration of a whole class: 

 Jackson says that the elongated siphon of Mya, the long-necked clam, 

 is due to its habit of burrowing in the mud, or to quote his words: 

 ' It seems very evident that the long siphon of this genus was brought 

 about by the effort to reach the surface, induced by the habit of deep 

 burial.' It certainly would be pertinent to inquire where it got this 

 habit, and how it happened to be transmitted. It is surely as diffi- 

 cult to explain the acquisition and inheritance of habits, the basis of 

 which we do not know, as it is to explain the acquisition and inheri- 

 tance of structures which are tangible and visible. Such a method 

 of procedure, in addition to begging the whole question, commits the 

 further sin of reasoning from the relatively unknown to the relatively 

 known. 



"This case is but a fair sample of a whole class, among which may 

 be mentioned the following: The derivation of the long hind legs of 

 jumping animals, the long forelegs of climbing animals, and the elon- 

 gation of all the legs of running animals through the influence of an 

 inherited habit. All such cases are open to the very serious objection 

 mentioned above. 



" Another whole class of arguments may be reduced to this propo- 

 sition: Because necessary mechanical conditions are never violated 

 by organisms, therefore modifications due to such conditions show 

 t lie inheritance of acquired characters. Plainly, the alternative propo- 

 sition is this: if acquired characters are not inherited, organisms ought 

 to do impossible things. 



"Many of the arguments advanced to prove the inheritance of 

 characters acquired through use or disuse seem to me to prove entirely 



