CLASSIFICATION. 49 



with variations in the lapse of time, is the foundation for classi- 

 fication. That plants Tary, some in one direction, others in 

 another, is now known to all with the causes therefor. Thus an 

 "early type became diversified, into varieties, then species, 

 genera, etc. 'Now classification should express, so far as can 

 be, the real reationships that must exist because of such a 

 descent of forms. 



Degeees of Likeness. — Classification would not be possible 

 if all fruits were alike, or if they differed by exactly the same 

 characters and to the same degree. But it is a matter of fact 

 that they exhibit very different degrees of likeness, theoretically 

 all degrees of likeness possible within the limits of their kind. 

 These degrees, we know, are the result of modifications in the 

 descent from a common ancestry. Now to systematically ar- 

 range fruits, and groups of fruits, according to their degrees of 

 likeness, or unlikeness, is to classify. If, as we have said before, 

 these degrees are founded upon nearness or remoteness of rela- 

 tionship in the process of evolution, classification becomes a 

 formulation of fruits into groups according to their natural 

 relationships. It is the problem first of botanical classification, 

 and then of pomological classification, to search out the rela- 

 tionships which, the structure of fruits and fruit plants indicate 

 and express them by dividing plants into groups, and sub-diyid- 

 ing these into groups according to the characters shared in com- 

 mon ; or in conformity to degrees of likeness ; or, again, accord- 

 ing to genealogical relationship. 



HoETicuLTUKAL Geoups. — Long ago botanists found it neces- 

 sary to group plants whereby the like came together and were 

 separated from the unlike. These groups were given names, as ; 

 class J order, genus, species, etc., and each was assigned a relative 



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