24 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



began to vary, but in the same way, though in differ- 

 ent degrees. By selecting seed from the best rooted 

 plants the acquired ' somatic' characters of an en- 

 larged root, glabrous leaves, etc. , became fixed and 

 hereditary; and the ' Student,' as he called it, having 

 been ' improved ' by Messrs. Sutton and Sons, is still 

 regarded as ' the best in the trade. ' This is definite 

 variation, according to Darwin's definition, for those 

 weeded out did not differ from the selected, morpho- 

 logically, except in degree, the variations towards im- 

 provement not being quite fast enough to entitle them 

 to survive.'* 



Finally I wish especially to point out that variation 

 in animals, and probably in plants, (with which I am 

 not so familiar,) gives no ground for believing that 

 "sports "have any considerable influence on the course 

 of evolution. This is apparent whether we view the 

 serial lines of variations of specific, generic, or higher 

 characters ; or whether we trace the phylogeny of the 

 animal and vegetable types by means of the paleonto- 

 logical record. The method of evolution has appar- 

 ently been one of successional increment or decrement 

 of parts along definite lines. More or less abruptness 

 in some of the steps of this succession there may have 

 been ; since a definite amount of energy expended in 

 a given direction at a given point of history might pro- 

 duce a much greater effect than the same amount ex- 

 pended at some other period or point of evolution. 

 This might be due to the release of stored energy, 

 which could only be accomplished by a coincidence of 

 circumstances. A simple illustration of the phenome- 

 non of abrupt metamorphosis is to be found in the 

 passage of matter from the gaseous to the liquid, and 



