428 



their stems and roots is composed of annual circles, in the 

 youngest or outermost of which the whole process of their 

 circulation, nourishment, and increase, for the present year, 

 is transacted. The number 5 and its compounds generally 

 prevail in their parts of fructification. 



These great primary distinctions being, in the main, 

 established, we proceed to principles of subdivision. In 

 these, what is technically called insertion, or the mode in 

 which one part is situated with respect to another, takes 

 the lead. Chiefly is to be considered whether the Ger- 

 men (the rudiment of the fruit or seed,) is below the other 

 parts of the flower or above them, inferior or superior. 



Next we are to notice how the Petals (coloured leaves 

 of a flower) if present, and the Stamens (organs of im- 

 pregnation) are connected with each other, or with the 

 Calyx (external covering). Lastly, whether the Stamens 

 and Pistils are situated in the same flower or in two di- 

 stinct ones of the same species. 



These several principles are the key to Jussieu's sy- 

 stem. The comparative value, or certainty, of each, we 

 shall investigate as we proceed. We must always keep 

 in mind that not one of them is, in every case, strictly ab- 

 solute, or without exception, in its interference with na- 

 tural orders, perhaps not even the great division of Mo- 

 nocotyledones and Dicotyledones. 



Hence, an ingenious French author, M. Richard, re- 

 jecting this, has divided plants, according to their mode 

 of germination, into Endorhizte and Exorhiza. 



The first, as the name imports, produce their root from 

 an internal tubercle, evolved in germination. In the others, 

 the lower point of the embryo itself becomes the root. 



Endorhizce are generally analogous to Monoeotyledones, 

 and Exorhizce to Dicotyledones. But besides the great 

 obscurity of these distinctions, nothing is gained by them. 

 They are liable to as many exceptions as the cotyledons. 



I have only now to add, that nothing like mathematical 

 certainty is to be found in the classification of plants. 



