XX.] IMPERFECT ADAPTATION. 339 



to shorten its life. This is an imaginary notion. 

 Plants are not so nicely balanced that comparatively 

 slight injury will disturb their equilibrium and 

 shorten their life. And even if the supposition were 

 true, it may be assumed that the increased attention 

 given to cultivation and fertilizing in later years 

 would counterbalance any weakness induced by in- 

 crease in incidental insect injury. 



3. Greater abundance of fungi. — The remarks 

 which have been made in reference to insects apply 

 equally to fungi. There are few augmentations in fun- 

 gous injuries which lessen the longevity of the tree. 



We have now eliminated the extra -cultural hypoth- 

 eses of failure in apple trees, — all those cases 

 which lie beyond the control of the grower. We 

 have now to consider those assumed causes which 

 are wholly or mostly under direct control of the 

 orchardist. 



4. Lack of adaptation of varieties to conditions. — 

 In our discussion of varietal difference, above, it was 

 observed that varieties of apples, as of other fruits, 

 differ widely among themselves in constitution. It is 

 very evident, therefore, that all varieties are not 

 equally adapted to trying conditions. We have yet 

 scarcely attempted to make any discriminating choice 

 of varieties in respect to their constitutions. It is 

 only within the last few years that search for ' ' iron - 

 clads" has been diligent, and much of this has been 

 random. 



It is also undoubtedly true that the same variety 

 is not equally adapted to all conditions. This is 

 really but another way of stating the above proposi- 

 tion, but it brings out an important point, viz.: 



