iSgj.j Elliot, ruhertftince of Actjiiired Characters. \0'X 



ainplcs that are qualitative, or "rise of structures that are essen- 

 tially new, and not simple modifications of pre-existing forms." 



One of them is the addition of new cusps, which do not rise at 

 random pi^ints and disappear, but successive cusps are added to 

 the simple conical crown at the point of the maximum wear. 

 There are rare exceptions to this fact, however, which will require 

 subsequent research to explain whether or not they are in con- 

 formity with the laws of individual adaptation. A very strik- 

 ing instance of the effects of use and disuse is cited also by Prof. 

 Osborne* derived from the ancient pedigree of the American 

 horse, where we are (to use the Professor's words) in before the 

 birth, so to speak, and the modifications in the leg from the 

 four-toed Hyracotheriufn to the eocene Mesohippus were 

 caused, as proved by various investigators including himself, by 

 the strain arising each time the foot was placed upon the ground 

 producing infinitesimal alterations in all the bones of the leg, and 

 "during the early geological periods these strains were constantly 

 changing pari passu., with the gradual decrease of the lateral, 

 and increase of the central digits." And in view of this evidence 

 we may all say with the writer of the article from which I have 

 quoted that "it is hard to believe with the new school, these invari- 

 able sequences of race adaptation on individual adaptation are not 

 instances of cause and effect. If they are, they afford absolute 

 proof of the transmission of acquired characters. If not, all our 

 pains-taking researches and vast literature lead to no result." 



I have thus as briefly as possible, though fully conscious of having 

 occupied more time than I ought, brought this extremely impor- 

 tant subject before you for your earnest consideration. It will 

 be readily perceived that I have merely touched upon a few of the 

 points that would naturally arise for discussion, in connection 

 with the transmission of acquired characters but my object, in 

 drawing your attention more particularly to this question, is to 

 excite your interest, in the hope that by your own individual 

 investigations and experiments you may be able to throw some 

 light on so much that now is obscure and impossible of expla- 

 nation. We none of us have the temerity, I trust, to say with a 

 distinguished botanistf that "the questions at issue with regard 

 to evolution are now thoroughly understood by biologists," but 



*Atlantic Monthly, 1891, p. 362. 

 tDyer, Nature, XLI, 1890, p. 315. 



