No. 510] PROBLEMS IN PLANT ECOLOGY 357 



bizarre to be applied to plants. A thing never to be lost 

 sight of is that evolution has taken place out of doors, 

 and that the contortions of a puny plant in our illy lighted 

 and gas-ridden laboratories do not solve our most im- 

 portant problems. In recent years no physiological work 

 of greater import has appeared than that from the Desert 

 Laboratory, where the direct stimulus to research has 

 been contributed by the desert itself and its ecological 

 problems. 



The developments of the past decade, therefore, make 

 it essential that physiology and ecology break down the 

 barrier erected for them in Madison in 1893, where it was 

 declared that physiology is experimental and ecology ob- 

 servational. The ecologist must experiment in order to 

 resolve a natural complex of factors into its individual 

 elements, while the physiologist must be a student of 

 field conditions, if he wishes to deal sanely with the 

 great problems connected with the evolution of form 

 and behavior. Recognizing, then, the interdependence if 

 not the complete identity of experimental ecology and 

 field physiology, it becomes necessary to consider the 

 underlying philosophy that serves as a motive for all 

 research along these lines. The importance of one's 

 philosophy upon his research can scarcely be overesti- 

 mated, for it determines the problems to be attacked, 

 the methods to be employed, and, on account of the per- 

 sonal equation, is likely to give some color to the results 

 secured. But it is not necessary that the working theory 

 be true; indeed it is often better that it be most untrue, 

 since it may thus lead to the testing ol' more theories than 

 might otherwise be employed. The fundamental test of 

 a working theory is that it be that one which will stimu- 

 late the maximum of discriminative research. There can 

 be given no better illustration of an unproductive theory 

 than the theory of vitalism. This supposes that there is 

 a fundamental difference between the living and the non- 

 living, hence one would not expect a vital ist to lead in 



