42 



The Plant World. 



the plants involved, is essentially the same for both lines of 

 study, but that of measuring environmental conditions is of 

 course much more difficult where the latter are uncontrolled. 



There is a principle of scientific research that in an investi- 

 gation which involves the measurement of a number of causal 

 factors and the relation of these factors to resulting conditions, 

 the various measurements must be of as nearly equal accuracy 

 as possible. Where a number of complex factors are to be 

 dealt with, as in ecology, progress must come from a refinement 

 of methods of measurement on the one hand and from better 

 interpretations of the data which result from the measurements 

 on the other. According to the principle just stated, we must 

 ever seek to improve those of our methods which are the least 

 accurate, not those which are the most easily susceptible cf 

 improvement. It is, indeed, often a waste cf energy to seek 

 the highest possible accuracy in all of a series of measurements 

 where one or more are at best of low accuracy. The accuracy 

 of the resulting summation must be subject roughly to the error 

 of the least accurate of the members. 



It is not my purpose to submit any recommendations as 

 to improvement in the general philosophy of ecology, although 

 we must all realize that one of our greatest hindrances at present 

 lies in the careless thinking which fills our literature with wrong 

 or at least misleading imaginings such as are suggested by 

 the Jonah-like words, adaptation, use, purpose, etc. It is to 

 lines along which, it appears to me, improved methods of meas- 

 urement are desirable, that I wish to call your attention at the 

 present time. Our methods for dealing with the plant responses, 

 with the effects of environment, already possess, in general, an 

 accuracy far surpassing that exhibited by the methods employed 

 in measuring the environmental conditions which act as causes. 

 I am unable to avoid mentioning, however, one phase of plant 

 measurement which has so far received an almost insignificant 

 minimum of attention both from physiologists and ecologists. 

 I refer to the subterranean portions of the plant. Considering 

 the undoubtedly great importance of the underground portions of 

 ordinary plants it would seem that these are well worthy of 

 more attention than has heretofore been accorded them. 



The complexity of natural environmental conditions makes 

 it necessary often to break them up into component parts and 



