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GEORGE E. NICHOLS Vo1 - IV > No - 1 



The Abstract-concrete Application of the Term Explained. Just what the 

 proposed interpretation of the term plant association implies can best be made 

 clear, perhaps, by describing a parallel application which we make of the 

 species concept, since the species is quite generally regarded as the taxonomic 

 counterpart of the association. For the sake of illustration let us take the 

 case of the white oak. From the comparative study of a number of indi- 

 viduals of this tree we formulate an abstract concept of " white oak." Then 

 we proceed to generalize: we take this abstract concept of white oak, this 

 creation of our minds, and we call any tree that conforms to it a white oak. 

 Going further, we speak of white oak in technical terms as a species, and we 

 give it a scientific name, Quercus alba. But, of course, while the species 

 concept is a modern one, the ideas on which this concept is based date back 

 to the dawn of human intelligence. 8 



With regard to the application of the species concept, then, the conclusion 

 seems inevitable that to all practical intents and purposes it should be taken 

 to include both the generalized concept and the concrete specimens or examples 

 upon which this concept is based. When I point to a particular tree and say, 

 " This is a white oak," or " This is Quercus alba," I am applying the species 

 concept in the concrete sense. When I say, " The white oak can be recognized 

 by the following characteristics," or "Quercus alba is distributed throughout 

 the eastern United States," I am applying the species concept in the abstract 

 sense. And there is no confusion of ideas in this double use. 



To return to the plant association. Interpreting the term in both the 

 abstract and the concrete senses, I can point to a particular pitch pine grove 

 and say, " This is a pitch pine association," and then in the same breath, if 

 that is physically possible, I can say, " The pitch pine association is character- 

 istic of sand plains throughout Connecticut." In the first statement I have 

 applied the term association in the concrete sense ; in the second I have given 

 it an abstract interpretation ; and here, again, there is no confusion of ideas. 



The Aggregate Concept of the Association. With regard to the applica- 

 tion of the term association to a specific aggregate of plant communities, e.g., 

 to all the pitch pine communities in existence considered as one concrete 

 whole, there is nothing in the generally accepted recommendation, as stated 

 above, which precludes this use. The abstract concept of pitch pine associ- 

 ation includes by implication not only all the pitch pine communities in exist- 

 ence, but all similar communities of the past and of the future as well ; and 



8 In logic, " The active mental process by which concepts are formed is commonly 

 said to fall into three stages: comparison, abstraction, and generalization" (Berkeley). 

 The mental process " whereby ideas taken from particular beings become general rep- 

 resentatives of all of the same kind" is termed abstraction (Locke). Wherever we 

 encounter two or more concrete objects of the same kind, by comparative study and 

 abstraction we formulate generalized or abstract concepts. Abstraction and generaliza- 

 tion form the basis of all classification. 



