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there is a not unnatural tendency on the i)art of niorpholoji^ists 

 and plnsiologists to consider ecology, or at least this part of it, 

 as equivalent to or included in their own subjects. Since these 

 subjects have accepted names, they ask "What is ecology?" 



Another expression of the interrelation between plant and 

 environment is seen in the restriction of a species to a particular 

 type of environment, that is, to a particular habitat. This 

 phenomenon can not be observed on a single indixidual, which is 

 of course restricted to a single station, but must be studied from 

 many individuals of one race. In this case the visible result is 

 apart from either morphology or physiology, and to some botan- 

 ists this alone is ecology, just as the behavior of a plant is physi- 

 ology*. But after all, the habitat-relation of a species is only 

 one type of behavior, dependent upon the physiological functions 

 of the single individual, but measured and tested by the behavior 

 of many individuals or of the race. 



It is hardly necessary to say that tangible or visible phenomena 

 are frequently noticed before the underlying processes or correla- 

 tions are discovered. Starch was known before photosynthesis; 

 growth of trees before cambium. The morphological effect of 

 ecological relations, such as alpine dwarfing, was known before 

 the causes, which are even yet not fully understood. Plant 

 associations were described long before their fundamental nature 

 was appreciated. 



In conclusion, let it be repeated that ecology is a division of 

 knowledge, to be studied only through perceptible phenomena, 

 which are frequently structural or functional in nature and there- 

 fore subjects for morphology and physiology also, but that the 

 questions which ecology seeks to answer, the knowledge which 

 it aims to supply, deal not with structure and function alone 

 but with the correlation between the plant as a whole and the 

 environment in which it grows. 

 New York Botanical Garden 



