ASPECTS OF KINETIC EVOLUTION 3 17 



The theory of determinants afforded, at most, a method of 

 thinking about the process of organic succession, but it does 

 not appear that this way of thinking is either correct or neces- 

 sary. It assumes a complete diversity of nature between ger- 

 minal and somatic cells, which the facts do not warrant, especi- 

 ally among plants, and it assumes further that there are definite 

 mechanical directive relations between the germ-cells and the 

 resulting organisms, which the facts also refuse to indicate. Of 

 the real nature of heredity we know, as yet, absolutely nothing, 

 any more than of analogous phenomena, instinct and memory. 

 Speculations, even of purely hypothetical character, may some- 

 times be of service in the treatment of scientific problems, but 

 no speculation should be cherished which hides or even casts a 

 shadow over facts. 



Under kinetic evolution the symbasic interbreeding of the 

 diverse individuals of the species is held to be the principal 

 agent of evolutionary change, since it is in this manner that the 

 prepotent variations which appear among the component indi- 

 viduals are transmitted and combined into the complex organic 

 result. Interbreeding is held to effect an integration of indi 

 vidual variations inside the species, instead of each variation 

 being considered a new species, as in the mutation theory. 



Symbasis is one of the general conditions of organic exist 

 ence, but under static theories its evolutionary significance was 

 so completely overlooked that no term was provided by which 

 it could be directly and definitely symbolized. The word in- 

 terbreeding, if used alone, would generally be misunderstood 

 in one of two opposite and equally unfortunate senses. Some 

 writers use interbreeding as synonymous with inbreeding or 

 close-breeding, and some for wide cross-breeding, which are 

 exactly the conditions to be avoided in the discussion of normal 

 specific relations. Another term being indispensable, symbasis 

 was introduced, in allusion to the fact that the individual mem- 

 bers of species are normally associated in groups. The expres- 

 sion also lends itself most conveniently to the description of 

 kinetic interpretations, in view of the fact that the association 

 of organisms into symbasic groups is looked upon as one of the 

 principal agencies of evolutionary progress. 



