ECOLOGY. 



INTRODUCTION. 



447. Life processes in the individual plant. — In studying 

 the phenomena of plant life which relate to the methods of 

 absorption and transportation of food to different parts of the 

 plant, and the internal processes of metabolism concerned in 

 the building up of new plant material, and the formation of 

 waste, as well as certain of the growth phenomena and irritable 

 properties, we have been dealing largely with the individual 

 plant. A study of these life processes we term physiology. 

 They relate to the immediate conditions of existence and well 

 being of the plant. 



448. Form in members of the plant body. — Beyond the very 

 simple plants of the lower groups, and a few reduced forms 

 among the higher plants, the plant body becomes more or less 

 bulky or enlarged, and each cell is so situated that it is unable 

 to participate equally in a number, or all, of the life processes. 

 The plant body therefore becomes more or less differentiated 

 into parts, which from the standpoint of physiology are organs 

 for the performance of distinct functions. This leads us in 

 the complex plant body to recognize form as an important cor- 

 relative of function in many cases. The immense variation 

 which has, through time, taken place in the development of 

 plants has resulted in a great diversity of form even in the 

 same members %f the plant body. Within certain limits, how- 

 ever, the form of the plant parts among the individuals of a 

 species is the same, and they are inherited by, or handed down 

 to, the offspring. 



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