INTRODUCTION 487 



which reside within the plant, but are external to the organ affected and 

 are not hereditary. For example, the influence of a stem upon the 

 development of its lateral branches is correlative; so far as the branches 

 are concerned, this is quite as external as are such factors as light and 

 humidity. 



Scarcely second in importance to the terms used are the terms avoided. 

 The standpoint of this book, contrary to that of many previous eco- 

 logical treatises, is that of mechanical causation rather than of teleology 

 and adaptation (see p. 947 for a discussion of ecologica! philosophy), 

 hence many familiar terms are here avoided; among such are 

 words like adaptation, adjustment, 1 accommodation, and regulation, pur- 

 posive words which are here replaced by the expression advantageous 

 reaction, thus recognizing that some activities are indifferent or disad- 

 vantageous. Two of the commonest and most insidious words con- 

 veying teleological implications are to and for, in such sentences as 

 " winged seeds are a mechanism for dispersal" and " plants close their 

 stomata and develop cutin to check transpiration." Words implying 

 forethought, such as reserve and storage, usually are omitted, as are 

 anthropomorphic words in general, particularly those suggestive of 

 emotion (such as hydrophile, xerophile, heliophobe, geophilous, entomoph- 

 ilous). Less objectionable, perhaps, but rather fanciful, are words or 

 expressions which imply that plants, like men, try to do things, as 

 conveyed in the familiar expression, struggle for existence, and in 

 such words as success, failure, or competition, as applied to plant be- 

 havior. Some words, in themselves unobjectionable, have been used so 

 generally with teleological implications, that they mostly are omitted; 

 for example, the word function has been employed so often in the 

 sense of purpose that role is used wherever feasible; similarly, reaction 

 usually is employed in place of response, though theoretically the latter 

 word is quite as good. The attempt is made generally to use words 

 that are equally applicable in physics and in chemistry ; especially is 

 this attempt worth while, because ecology, more than any other phase 

 of biology, has suffered from the unrestricted use of anthropomorphic 

 similes and teleological fantasies. 



It is realized that language lags behind ideas, that we still speak of 



1 Such terms as adaptation and adjustment, when used in the sense of a state, rather 

 than in the sense of a process, are relatively unobjectionable, but in view of their large 

 past use in the latter sense, they are liable to lead to confusion and hence are omitted in all 

 senses. 



