284 ECOLOGY. 



449. Form as indicating relationship. Where the form of 

 a member is a constant peculiarity of the plants of one kind, 

 differences in form among other plants indicate that there are 

 other kinds, or species, of plants. So that aside from the rela- 

 tion which the members of the plant, as organs, bear to the 

 immediate life functions, the form of the members becomes the 

 measure of the value of relationships among kinds. The study of 

 form in this connection we term morphology. 



450. Relation of physiology and morphology. While physi- 

 ology and morphology are regarded as distinct subjects, still we 

 see how they are interrelated when we consider the details of 

 one or the other subject. It is in the broader concept that the 

 two subjects are fundamentally different. 



451. Form and function in a broader sense than the indi- 

 vidual. Just as the individual life processes relate chiefly to 

 the immediate conditions of existence of the plant, and as the 

 individualized form of the members relates to the immediate 

 conditions of relationship; so the life processes in general, on 

 a grand scale or as affected by seasons, or mutual relations, as 

 well as form on a grand scale, relate to more extended condi- 

 tions of existence, and to relationships, the measure of which 

 is not the form of the plant itself, but the form of the plant 

 community, showing a relationship of different kinds under like 

 conditions of existence. In this sense we are concerned with 

 those processes and forms which are influenced by, or lay hold 

 on, environment. By the environment is meant all the sur- 

 rounding objects, conditions, and forces operating in nature, 

 either temporary, seasonal, or permanent. 



452. Mutual and environmental relationships. While we 

 are engaged with the study of the life processes concerned 

 in nutrition and growth of plants, with the details of form, struc- 

 ture, and systematic relationship, we should not overlook the 

 mutual relationships which exist among plants in their natural 

 habitat, and the phenomena of growth recurring with the 

 seasons, and influenced by environment, or due to inherent 



