III.] CONCLUSIONS. 105 



apt to be capable of endless contractions and modifica- 

 tions to meet individual cases. I sometimes think that 

 we are substituting for the philosophy of observation a 

 philosophy of definitions. 



I have now attempted to show: 



1. That the plant is not a simple autonomy in the 

 sense in which the animal is. 



2. That its parts are virtually independent in respect 

 to (a) propagation (equally either when detached or still 

 persisting upon the parent plant), (6) struggle for ex- 

 istence amongst themselves, (c) variation, (d) trans- 

 mission of their characters by means of either seeds or 

 buds. 



3. That there is no essential difference between bud- 

 varieties and seed -varieties, apart from the mere fact of 

 their unlike derivation; and the causes of variation in 

 the one case are the same as those in the other. 



4. That all these parts or phytons are at first sexless, 

 but finally may or may not develop sex. 



5. That much of the evolution of the vegetable king- 

 dom is accomplished by wholly sexless means. 



There is, then, a fundamental unlikeness in the ulti- 

 mate evolution of animals and plants. A plant, as we 

 ordinarily know it, is a colony of potential individuals, 

 and each individual save the very first is derived from 

 an asexual parent, yet each one may, and usually does, 

 develop sex. Each individual is capable also of receiv- 

 ing a distinct or peculiar influence of the environment 

 and struggle for existence, and is capable, therefore, of 

 independent permanent modification. It is not possible, 

 therefore, that there is any localization or continuity of 

 a germ -plasm in the sense in which these conceptions 

 are applied to animals; nor is it possible for the plant, 



