PART III ECOLOGY 



INTRODUCTION 



The scope of ecology. Ecology is a science in its beginnings. 

 Already it has a great body of data and theories whose validity is more 

 or less established, but whose systematic organization scarcely has 

 been attempted. Nor is it possible as yet to mark out its limits, for it 

 overlaps to a greater or less degree every other field of biology, and of 

 physiography and geology as well. Speaking broadly, ecology considers 

 organisms in relation to their environment. Somewhat more precisely, 

 ecology is that phase of biology that endeavors to explain the origin, 

 variation, and role of plant or animal structures, and the origin and 

 variation of plant or animal associations. 



Plant ecology has a twofold aspect : the one considers the individual 

 organism and its component parts as related to environment ; this, 

 since it overlaps morphology and physiology, may be called morpho- 

 logical and physiological ecology, or the ecology of plant structure and 

 behavior. The other aspect considers plants en masse as related to 

 soil and climate; this, since it overlaps physiography, may be called 

 physiographic ecology, or the ecology of vegetation. 1 Morphological 

 and physiological ecology consider the same materials as do morphology 

 and physiology, but largely from a different point of view. Morphology 

 deals with structure and physiology with behavior, whereas ecology relates 

 both structure and behavior to external conditions, paying attention 

 chiefly to the cause and the significance of environmental variations. 

 Morphology and physiology are essentially laboratory sciences, while 

 ecology is in the main a science of the field, treating organisms as they 

 grow in nature. 



Since ecology overlaps various sciences, it is less a simple science than 

 a science complex; its adequate study presupposes a foundation in the 

 basic principles of physics, chemistry, morphology, and physiology, 



1 Recently proposed terms for the ecology of the individual organism and for that 

 of organisms en masse are, respectively, auiecology and synecology. 



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