INFLUENCE OF CROSS-FEETILIZATION. 235 



When a tree is able to take and prepare more food than it 

 can readily use in forming wood, it uses this surplus in making 

 fruit — young apple-trees that are about to die from injury to 

 the trunk or roots are apt to spend what little strength they 

 have in producing blossoms and fruit, and I notice now, as 

 our beautiful maples are dying from the action of the borers, 

 that the year before they die they are perfectly loaded with 

 fruit. The fact seems to be that all organisms are so consti- 

 tuted that when they must soon pass away by natural causes, 

 the very process by which they pass away hastens in them 

 the production of seed, so that the species may be preserved. 

 It is through the flower-bud mainly that we secure variation, 

 and certainly in this light alone, the sexuality of trees and 

 other plants is a wonderful provision for man, giving him 

 such marvellous power over them. President Wilder and 

 others have done so much for us in this direction that I 

 need say no more on this point. But there is one suggestion 

 that I wish to make for your observation and experiment. 

 We accept the fact that the seed is changed by cross-fertiliza- 

 tion, but we seem to take it for granted that the covering of 

 the seed, that is, our "soft fruits," are not affected by cross- 

 fertilization. I am disposed to think this is a mistake, that 

 the fruits of certain plants are sensibly affected by the pollen 

 from others. 



Mr. Darwin has given * apparently well authenticated cases 

 of the influence of pollen in changing the character of the 

 covering of the seed in plants of very different kind, aspease, 

 palm-fruit, oranges, melons, and grapes. The paragraph 

 relating to apples we quote as follows : — 



"No case of the direct action of the pollen of one variety on 

 another is better authenticated, or more remarkable, than that of the 

 common apple. The fruit here consists of the lower part of the 

 calyx, and of the upper part of the flower-peduncle, in a metamor- 

 phosed condition, so that the effect of the foreign pollen has extend- 

 ed even beyond the limits of the ovarium. Cases of apples thus 

 affected were recorded by Bradley in the early part of the last cen- 

 tury ; and other cases are given in old volumes of the Philosophical 

 Transactions ; in one of these, a russeting apple and an adjoining 

 kind mutually affected each other's fruit ; and in another case a 



* Animals and Plants under Domestication. Vol. 1, pp. 479-81. 



