74 HISTORY OF BOTANY 



PROGRESS IN TAXONOMY AND ANATOMY AT THE 

 BEGINNING OF THE NINETEENTH CENTURY 



The next important step in advance in the natural 

 classification of plants was taken by two representatives 

 of a very distinguished family, that of De Candolle 

 in Switzerland. August Pyrame de Candolle, the elder 

 of the two men whose names have become household 

 words in the history of botany, based his classification 

 on that of De Jussieu, but modified it greatly in accordance 

 with certain principles which he elaborated in a volume 

 called Theorie elementaire de la botanique, published in 

 1813. The chief thesis he sets out to establish is that 

 morphology is the key to taxonomy, and that physiology 

 for this purpose is not only useless but actually mis- 

 leading. His first task is to define and illustrate the 

 doctrine of symmetry of organs. This, he says, necessi- 

 tates the comparison of a large number of forms, and 

 such a comparison discloses the fact that the difficulties 

 in the way of the recognition of relationship between 

 forms that are in reality quite closely akin are due to 

 three causes, abortion of parts, degeneration of parts, 

 and adherence of parts of one kind to parts of another 

 kind. " The whole art of natural classification," he says, 

 " consists in discovering the plan of symmetry/' 



While holding such views, De Candolle was, strange 

 to say, a believer in the doctrine of the constancy of 

 species, and it is remarkable that he succeeded in main- 

 taining this belief and at the same time propounding the 

 view that organs might degenerate, or even abort, or 

 unite with other organs. If a plant possessed four 

 stamens and a staminode when, according to the doctrine 

 of symmetry it ought to have had five functional stamens, 

 it must either have been created with a staminode in 

 place of the fifth functional stamen, and then there could 

 be no degeneration, or it must have been derived from 

 a plant with five functional stamens, and then there 



