120 



GENERIC DISTINCTIONS, 



CHAP. XXIX. 

 OF GENERIC DISTINCTIONS, 



HAVING now gone through the explanation of the Classes 

 and Orders of the system, we come to the distinctions of the 

 Genera. These, by the theory of the Sexual System, are to be 

 regulated by the fructification only. The parts of fructification 

 known to the earlier botanists were few, and might be well 

 thought insufficient for distinguishing the vegetable productions 

 of nature : they therefore had recourse to the habit of plants, 

 and other circumstances ; and by this means a great number of 

 genera were established, which the new system is obliged to re- 

 ject. Of these we shall give the reader an ample list of in- 

 stances in Chap. XXXI. 



The fructification being admitted as the only foundation of the 

 generic distinctions all vegetables that agree in their parts of 

 fructification are to be put together under one genus ; and all 

 such as differ in those parts, are to be divided. The character- 

 istic mark of each genus is to be fixed from the number, figure, 

 proportion, and situation, of all the parts : but as there are few 

 genera wherein all the parts are constant in everyone of the spe- 

 cies, we ought, wherever it is possible, to fix upon some one sin- 

 gle circumstance that is constant, and make it the essential cha- 

 racter. This in most genera may be had : thus the essence of 

 Prunella, Torenia, Euphrasia, Alyssum, and Crambe, lies 

 in the denticles of the stamina that of Curcuma, Chelone, Bjg- 

 nonia, and Marty n i a, in a mutilated stamen the Ranunculus 

 is distinguished by its nectarium, which is a pore in the claw r s of 

 its petals ;...Hydrophyllum by the same part, which in that ge- 

 nus is a closed chink in the laciniae of the corolla j... and Helle- 



