308 VEGETABLE ORCxANOGRAPHY. 



regular laws, and ascending from partial to general 

 facts, they were enabled to recognise the laws of sym- 

 metry a posteriori. 



Those who are attached to the second of these two 

 methods perform two parts in the general economy of 

 the science : on the one hand, they collect with care all 

 the facts in detail in order to derive general laws which, 

 gradually compared together, may lead to other laws a 

 little more general ; on the other hand, they examine 

 as simple hypotheses, to be verified or rejected, opinions 

 conceived a priori, and try to perceive in what points 

 the partial laws which they have recognised approach, 

 or from what they depart. This course appears to me 

 the same as that which is followed in all the physical 

 sciences, the only one which can lead to general truths. 

 If there still exist botanists who can believe, either 

 that there are no general laws in the structure of orga- 

 nized beings, or that it is not worth while to search 

 them out, I am persuaded that it can only result either 

 from their being frightened by the multitude of facts in 

 detail, or from their having studied only a small number 

 of objects selected without method from those found 

 within their reach. 



I shall now proceed to give a summary of this work 

 under an aphoristical form, which may be able to 

 give some idea of these principles of symmetry ; this 

 will be the object of the following chapter. 



