OF WASHINGTON. 19 



group, viewed in contrast with its structural and evolutionary 

 diversity. 



And since such facts are numerous in other fields of biology, 

 there appears to be justification for the view that evolution is a 

 kinetic phenomenon, or an active process of change, from the 

 standpoint of the organism, instead of the result of a passive 

 subjection to external interference in otherwise stable conditions. 



The static character of many evolutionary theories is obvious, 

 and even those which depend upon physical or chemical lability as 

 the moving force in vital phenomena, predicate, in effect, a tendency 

 to stable equilibrium. The contrary view is that evolution is one 

 of the normal properties of protoplasmic organisms ; change is the 

 law, the various forms of selection and isolation are the incidents. 

 Underneath the minor fluctuations which have been denomi 

 nated " fortuitous variations," is a continuous motion, though not 

 in a fixed direction. The minor variations may be looked upon 

 as ' k feelers '" for lines of least resistance, but motion there must 

 be. Selection or isolation may accelerate or retard the evolution 

 of the species, but permanent fixity of type the breeders of plants 

 and animals have long since found impossible. 



A kinetic theory of organic succession is not without bearing 

 upon other evolutionary questions. For example, the acquisi 

 tion of new characters, as in the case of the dorsal processes of 

 the Oxydesmidas, becomes, in a sense, an axiomatic proposition 

 requiring no special explanation apart from the facts of normal 

 reproduction. Heredity to the extent of absolute duplication 

 does not appear as a part of the programme of nature, and im 

 partially fortuitous variation in any character or characters could 

 result only in a stable, non-progressive average a state of specific 

 equilibrium. To disturb this and make evolution possible, it has 

 been believed necessary that selection or other external stimuli 

 must be universally predicated. Under the kinetic view, varia 

 tions may be supposed to arise and to be preserved as a part of 

 the normal and necessary process of change, or because they are 

 variations. The nature of the causes of change is not revealed, 

 but it can be understood that the progressive modifications of suc 

 cessive individuals may not be different in kind, or in any way 

 more mysterious than those of the single individual, except from 

 the standpoint of biologists who have invented complicated me 

 chanical theories to account for what have appeared to them as 

 temporary disturbances of otherwise stable conditions. 



The utility of a variation is not determined by the organism, 

 but depends upon the conditions encountered, and the testimony 

 of such groups as the Diplopoda indicates the impartial preserva 

 tion of useful and useless characters. Selection works by elimi 

 nation and affects the descendants of the survivors only as an 

 active form of isolation by limiting descent to those in which the 



