ECOLOGY. 

 INTRODUCTION. 



561. While we are engaged with the study of the life pro- 

 cesses concerned in nutrition and growth of plants, with the 

 details of form, structure, 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 qualities. By a study of the life histories of plants, 

 their habits and behavior under different conditions of environ- 

 ment, we shall broaden our concept of nature and cultivate our 

 aesthetic, observational, and reasoning faculties. The subject is 

 too large for full treatment within the limits of a part of an 

 elementary book. The way here can only be pointed out, and 

 the few examples and illustrations, it is hoped, will serve to open 

 the book of nature to the young student, and lead him to study 

 some of the problems which are presented by every region. 

 This study of plants, in their mutual and environmental relation- 

 ships, is ecology. 



562. For beginning classes, where only a small part of the 

 time is available, excursions can be made from time to time dur- 

 ing the year for this purpose, taking certain subjects for each ex- 

 cursion. For example, in the autumn one may study means for 

 the dissemination of seeds, protection of seeds, plant formations, 

 zonal distribution of plants, formation of early spring flowers, 

 etc. ; in the winter, twigs and buds, protection of plants against 

 the cold ; and in the spring, opening of the buds and flowers, 

 pollenation, etc. , and farther studies on plant societies, relation 

 of plants to soil, topography, etc. 



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