K.— BOTANY 233 



The retention of plant physiology within the domain of Botany has 

 saved us from the worst evils of the study of form unrelated to function. 

 This has also been one of the chief factors which led to that synthetic 

 approach to our subject which concerns the relation of the plant to its 

 surroundings. The supreme value of ecology, however, lies not so much 

 in the attention which it focusses upon the mutual relations of organisms or 

 even upon their relation to the environment, but in the synthesis which 

 ecology achieves, into a single picture, of so many aspects of Botany 

 itself and so many branches of human knowledge. Its high educational 

 and cultural potentiality is an outcome of the fact that it is the very anti- 

 thesis of that common failing of the human mind to think of different 

 subjects as isolated compartments of knowledge and not as different facets 

 of one and the same jewel. 



When we attempt to understand any plant community the necessary 

 study of the physical environment leads us at once into realms of soil 

 structure, into the physical problems connected with water retention and 

 water movement involving colloid properties and surface action. So, too, 

 the chemist and the meteorologist make their contributions to our concept 

 of the habitat, whilst the bacteriologist, the mycologist, and the proto- 

 zoologist all help us to envisage that teeming population of bacteria, 

 fungi and protozoa in the soil which, by their proper balance, maintain 

 a healthy circulation of chemical products and are a necessity for the 

 maintenance of the supply of raw material for the higher plants and 

 animals. 



But, since the environment of the present is in some considerable 

 degree the consequence of that of the immediate and sometimes of the 

 remote past, the study of external conditions brings us into contact with 

 the contributions of glaciologists and historians, whilst even the student of 

 ' place names ' may materially assist in the reconstruction of those past 

 conditions that in part have determined the present state. 



When we turn from the study of the habitat to that of the vegetation 

 which it supports we are at once confronted with the question as to the 

 extent to which the one is in equilibrium with the other. 



The morphologist and the anatomist furnish the data upon which we 

 base our judgment as to the degree to which the external form and internal 

 structure have contributed to render the organisms suited to the environ- 

 ments that they frequent. In so far as there is adaptation, whether 

 passive or active, in this respect, to that extent the community is in equi- 

 librium with its surroundings and represents a climax, subject it is true 

 to secular change but of a relatively stable character. 



The contribution of the systematist is to distinguish between the more 

 critical species and races which exhibit a localisation that less meticulous 

 examination might readily ignore and which often have an ecological im- 

 portance far greater than the Linneons of which they are the segregates. 

 The experimental conclusions of the physiologist in the laboratory must be 

 applied by the ecologist to the elucidation of problems in the field com- 

 plicated and often profoundly modified by the continual operation of the 

 competitive factor. 



Finally, knowledge of the life histories of the constituent organisms, the 

 reaction of the various phases of their development to the environment, 

 their modes of reproduction, their establishment and extension, comprise 



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