Characters as Adaptive and Specific. 201 



exercise a potent, an uniform, and a permanent in- 

 fluence on specific characters. 



With regard to plants, Darwin adduces a number 

 of facts to show the effects of climate on wheat, 

 cabbages, and other vegetables. Here, for example, 

 is what he says with regard to maize imported 

 from America to Germany : — 



" During the first year the plants were twelve feet high, and 

 a few seeds were perfected ; the lower seeds in the ear kept 

 true to their proper form, but the upper seeds became slightly 

 'changed. In the second generation the plants were from nine 

 to ten feet high, and ripened their seed better ; the depression 

 on the outer side of the seed had almost disappeared, and the 

 original beautiful white colour had become duskier. Some 

 of the seeds had even become yellow, and in their now rounded 

 form they approached the common European maize. In the 

 third generation nearly all resemblance to the original and very 

 distinct American parent-form was lost '." 



As these " highly remarkable " changes were effected 

 in but three generations, it is obvious that they 

 cannot have been dependent on selection of any 

 kind. The same remark applies to trees. Thus, — 



" Mr. Meehan has compared twenty-nine kinds of American 

 trees with their nearest European allies, all grown in close 

 proximity and under as nearly as possible the same conditions. 

 In the American species he finds, with the rarest exceptions, 

 that the leaves fall earlier in the season, and assume before their 

 fall a brighter tint ; that they are less deeply toothed or serrated ; 

 that the buds are smaller ; that the trees are more diffuse in 

 growth and have fewer branchlets ; and, lastly, that the seeds 

 are smaller — all in comparison with the corresponding European 

 species. Now, considering that these corresponding trees 



' Variation, See. vol. i. p. 340. 



