PROGRESS TOWARDS A NATURAL SYSTEM. 373 



structure and organization of the plant. The ap- 

 prehension of the due rank of this distinction has 

 gradually grown clearer. Cuvier 9 conceives that he 

 finds such a division clearly marked in Lobel, in 

 1581, and employed by Ray as the basis of his 

 classification a century later. This difference has 

 had its due place assigned it in more recent sys- 

 tems of arrangement ; but it is only later still that 

 its full import has been distinctly brought into view. 

 Desfontaines discovered 10 that the ligneous fibre is 

 developed in an opposite manner in vegetables with 

 one and with two cotyledons ; towards the inside 

 in the former case, and towards the outside in the 

 latter; and hence these two great classes have 

 been since termed endogenous and exogenous. 



Thus this division, according to the cotyledons, 

 appears to have the stamp of reality put upon it, 

 by acquiring a physiological meaning. Yet we are 

 not allowed to forget, even at this elevated point 

 of generalization, that no one character can be 

 imperative in a natural method. Lamarck, who 

 employed his great talents on botany, before he 

 devoted himself exclusively to other branches of 

 natural history, published his views concerning me- 

 thods, systems 11 , and characters. His main principle 

 is, that no single part of a plant, however essential, 



9 Hist. Sc. Nat. ii. 197- 10 Ib. i. pp. 196, 290. 



11 Sprengel ii. 296 ; and, there quoted, Flore Frangaise, t. i. 3, 

 1778. Mem. Ac. P. 1785. Journ. Hist. Nat. t. i. For La- 

 marck's Methode Analytique, see Dumeril, Sc. Nal. i. Art. 390. 



