Ic6 THE AMERICAN NATURALIST [Vol. LI 



induced are reversible, the long period under environ- 

 ment A should have produced a deep impression on 

 species X. Change under environment B should be slow. 

 Eeversal should be rapid, however, because of the slight 

 impression environment B must be supposed to have 

 made during the very few generations in which its influ- 

 ence was possible. 



If acquired characters are not inherited, precisely the 

 same changes should occur, owing to somatic adaptation, 

 the only differences being that the total amount of change 

 in each case would be reached in the second generation 

 after the environment had acted during the earliest stages 

 of the life history. 



If, on the other hand, the changes induced by environ- 

 ment B are not reversible, judgment must be based on 

 the percentage of individuals changed by B and not re- 

 changed by A. One can readily see how a just judgment 

 would be clouded by probable reversible somatic effects 

 in such' cases. Instances of the inheritance of acquire- 

 ments, unless they were very frequent, which from our 

 general evidence is unthinkable, would be indistinguish- 

 able from ordinary chance variations. 



Such methods of attack on the subject being almost 

 predestined to failure from the inherent difficulties of 

 the problem, it would seem wiser to seek for a more hope- 

 ful methodology, and in the meantime to accept the only 

 conclusion justified by the data at hand; namely, the 

 inheritance of acquired characters is either so rare an 

 occurrence or so slow a process, that by plant-breeders 

 it may be assumed to be non-existent. One realizes of 

 course that the problem of sexual transmission of somatic 

 acquirements is not necessarily the same as that of asex- 

 ual transmission, but the experimental results have been 

 the same in both cases. Let us, admit, therefore, that 

 one can not hope to obtain real improvement in asexually 

 propagated varieties merely by selecting buds from 

 plants or parts of plants which have developed under 

 especially favorable conditions. 



This does not mean that radical environmental changes 



