Characters as Adaptive and Specific. 239 



to negative their assumption for example, that 

 a diagnostic character in species of the genus Hiera- 

 tium is found by transplantation not to be hereditary, 

 or that the several named species of British trout 

 are similarly proved to be all " local varieties " of one 

 another. But, in point of fact, there ought to be 

 nothing to surprise us in such results unless, indeed, 

 it is the unwarrantable nature of the assumption that 

 any given differences of size, form, colour, &c., which 

 naturalists may have regarded as of specific value, 

 are, on this account, hereditary. Indeed, so sur- 

 prising is this assumption in the face of what we 

 know touching both the extent and the constancy 

 of climatic variation, that it seems to me such a 

 naturalist as Kerner, who never considers the 

 criterion of heredity at all, is less assailable than those 

 who profess to constitute this their chief criterion 

 of specific distinction. For it is certain that whatever 

 their professions may have nowadays become, sys- 

 tematic naturalists have never been in the habit 

 of really following this criterion. In theory they have 

 of late years attached more and more weight to 

 definition No. 4 ; but in practice they have always 

 adopted definition No. 3. The consequence is, that 

 in literally numberless cases (particularly in the 

 vegetable kingdom) "specific characters" are assumed 

 to be hereditary characters merely because systematic 

 naturalists have bestowed a specific name on the 

 form which presents them. Nor is this all. For, 

 conversely, even when it is known that constant mor- 

 phological characters are unquestionably hereditary 

 characters, if they happen to present but small 

 degrees of divergence from those of allied forms, then 



