CHA.P.III.] the Dogma of Constancy of Species. 135 



only be solved forty years later by Darwin's theory of selection. 

 A genuine inductive process alone could reveal these re- 

 markable relations between the morphological and physio- 

 logical characters of organs. But it is at the same time true 

 that De Candolle could not have made this discovery, if his 

 predecessors had not already established a large number of 

 affinities. It was while he was engaged in an exact comparison 

 of forms already recognised as undoubtedly related to one 

 another, that that which he called the plan of symmetry, and 

 which was afterwards named a type, revealed itself to him ; and as 

 he examined it more closely, and compared it with peculiarities 

 of habit in different plants formed on the same plan, he 

 discovered certain causes, by means of which the deviations 

 were to be explained ; these were abortion, degeneration, and 

 adherence. By attending to these he succeeded in discovering 

 affinities that had been hitherto doubtful or unknown; this 

 was at all events the true inductive way of advancing the 

 system, and whatever the earlier systematists had effected that 

 was really valuable had been effected virtually in the same 

 way, only they never arrived at a clear understanding of their 

 own mode of proceeding; they had followed unconsciously the 

 method which De Candolle clearly understood and consciously 

 pursued. 



The majority of De Candolle's successors were far from 

 fully appreciating the entire significance of his theory, its 

 importance as a matter of method and principle; on the 

 contrary in the search for affinities they continued to surrender 

 themselves to a blind feeling rather than to a clearly recognised 

 method, and the same must be said unhappily of De Candolle 

 himself, when he was dealing with the establishment of the 

 large divisions of the vegetable kingdom. With equal surprise 

 we find him in the book before us, in which he has developed 

 the true method in systematic botany, expressing the opinion 

 that the most important physiological characters must be 

 employed for the primary divisions of the system, and this 



