ASPECTS OF KINETIC EVOLUTION 201 



sarily so. A Guatemalan variety of the cotton plant takes on 

 in Texas a robust, upright habit of growth very distinct from 

 that of its Central American ancestor. It might be held that 

 this deviation from the previous type serves a purpose in the 

 internal economy of the plants, in enabling them to carry on 

 more efficiently the process of vegetative development. Never- 

 theless, it cannot be reckoned as a truly adaptive change, since 

 it does not improve the chances of the survival of the variety in 

 the new environment. These very large and vigorous plants 

 are relatively infertile, and ripen their fruits much later than 

 those which retain the normal low-growing parental form. This 

 behavior of the cotton plant is not the exception, but accords 

 with a general tendency of tropical plants toward excessive 

 vegetative development when first planted in northern latitudes. 

 The longer days and higher temperatures of our summer seasons 

 are not utilized for earlier and larger production of fruit, but are 

 wasted in riotous vegetative expansion often cut short by frost 

 before a single seed has been formed. 



New environments may also throw plants into a condition of 

 morphological instability* which can scarcely have any relation 

 to adaptation, since the result is an endless diversity of abrupt 

 variations or mutations along many different lines, including the 

 most opposite. The hereditary coherence of the species or 

 variety is lost, and the individuals scatter, as it were, in all direc- 

 tions. This explosive type of variation is occasioned, obviously, 

 by changes of environment, but it is equally obvious that one 

 and the same change of environment cannot be directly described 

 as having caused many diverse variations ; it need only be 

 thought of as having occasioned an abnormal intensification of 

 normal individual diversity. 



In some manner, quite unknown as yet, changes of conditions 

 do induce changes of methods of development, but to infer that 

 these changes are always advantageous, or that the external 

 causes actuate the modified development of the organisms, is 

 bad logic and worse biology. 



Curiously enough, it is only at one particular point that such 

 reckless conclusions are indulged. When we find a dozen dif- 

 ferent species of plants growing on the same square yard of soil, 



