INHERIT A.\CE OF ACQUIPTD CHARACTERS 100 



remarks: " Considerinf!; tlic width did d{'j)tli of tlie cfTocts 

 which the acceptance of one or the oth(>r of these liypotlieses 

 must have on our views of hfe, the question, Wliich of them is 

 tfue? demands beyond all other ({uestions whatever the atten- 

 tion of scientific men." 



Other illustrations of the supposed effect of use and disuse 

 are thuG discussed by Dr. Edwin Grant Conklin: 



"In the first place, this whole line of arj2;umont starts with the 

 assumption that the individual habits of an animal arc iiilicritcd, and 

 that these habits ultimately determine the structure, an assumption 

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

 any habit must be some physical structure, and if modifio<i haljits 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 nmd, or to ({uote 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 deej) 

 burial.' It certainly would be pertinent to in([uire 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 inlieri- 

 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 wliich 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 rumiing 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 

 the inheritance of acquired characters. Plainly, the alternative j)ropo^ 

 sition is this: if acquired characters t^re not inhonted, organisms ought 

 to do impossible things. 



''Many of the arguments advanced to prove the inheritance of 

 pbf^rftGt^rs aoqiurt?4 throvigh ^se or Jiguse seem to me to prove ep^i^iy 



