64 THE BOOK OP ROSES. 



Monsieur de Mirbel defines a species as " com- 

 posed of a succession of individuals produced 

 from each other by direct and constant genera- 

 tion, whether effected by seed, or by a simple 

 separation of parts." But this definition is 

 insufficient, in failing to inform us by what 

 physiological properties the species is to be 

 distinguished as generic, instead of as the vari- 

 ety of a species. Monsieur de Mirbel adds, 

 " We usually find in an individual the aggregate 

 of characters which distinguish the species to 

 which it belongs from all other species of the 

 vegetable kingdom." The term " aggregate of 

 characters," is not sufficiently explicit for a 

 definition. It is clear, however, that the au- 

 thor had in view superficial character ; for he 

 adds, that after having seen a white lily, no 

 one would confound it with the martagon, or 

 fritillary. 



We conceive that in many plants the diffe- 

 rent species are easily confounded ; as in violets, 

 aloes, amaryllises, pines, &c. &c. 



But instead of further citations of opinion, 

 let us proceed at once to consider what ought, 

 in the order of nature, to be considered a spe- 

 cies, and what a variety. 



A SPECIES ought to be composed of indivi- 

 duals produced from each other by successive 

 generations, and resembling each other in one 

 or more invariable specific characters. 



