238 Darwin, and after Darwin. 



regarded as presenting also an adaptive, or life- 

 serving, value? I will now endeavour to show that 

 there are certain very good reasons for answering 

 this question in the negative. 



(A.) 



In the first place, even if the modifications induced 

 by the direct action of a changed environment are 

 not hereditary, who is to know that they are not? 

 Assuredly not the botanist or zoologist who in 

 a particular area finds what he is fully entitled to 

 regard . as a well-marked specific type. Only by 

 experiments in transposition could it be proved 

 that the modifications have been produced by local 

 conditions ; and although the researches of many 

 experimentalists have shown how considerable and 

 how constant such modifications may be, where is the 

 systematic botanist who would ever think of trans- 

 planting an apparently new species from one distant 

 area to another before he concludes that it is a new 

 species? Or where is the systematic zoologist who 

 would take the trouble to transport what appears 

 to be an obviously endemic species of animal from 

 one country to another before venturing to give it 

 a new specific name? No doubt, both in the case 

 of plants and animals, it is tacitly assumed that 

 constant differences, if sufficient in amount to be re- 

 garded as specific differences are hereditary ; but there 

 is not one case in a hundred where the validity of this 

 assumption has ever been tested by experiments 

 in transposition. . Therefore naturalists are apt to 

 regard it as remarkable when the few experiments 

 which have been made in this direction are found 



