AN ECOLOGICAL ASPECT OF THE CONCEPTION 

 OF SPECIES 



DR. H. C. COWLES 



In the discussion of this question I do not feel myself 

 hedged in by any limitations, since no one pretends to 

 say what are the bounds of ecology. Indeed, to define 

 a species may be regarded as an easy task, compared 

 with the task of one who sets out to define ecology. And 

 so this occasion affords me a pleasant opportunity to 

 present some views for which I have long desired an 

 audience like this. 



It is coming to be realized that the problems of physiol- 

 ogy and ecology are essentially identical, not alone in 

 the matter of the species concept, but in all respects. 

 Physiologists and ecologists have come to feel that the 

 experimental method furnishes the only adequate test 

 for determining the validity of species. ' The method of 

 approach has differed with the point of view, and it is 

 the physiologist who has given most emphasis to the 

 fundamental importance of experimentation. The ecol- 

 ogist, on the other hand, has brought in the rich contribu- 

 tions of field observation. It is only recently that each 

 has recognized the imperative necessity of the method 

 of the other, and it now seems possible to predict that the 

 fundamental method of the future is to be field experi- 

 mentation combined with observation. No one realizes 

 so well as does the ecologist the inadequacy of laboratory 



ecologist feels that the species problem is essentially a 

 field problem, and hence incapable of final settlement, 

 either in the herbarium or in the laboratory. Yet it is 

 the exact methods of the laboratory carried into the 



