368 POLYGAMIA. 



florets, that there can be no doubt of the propriety 

 of classing its genera simply by the number of their 

 stamens and styles, which are very constant. 



2. Dioecia. The different flowers on two different 

 plants. I can scarcely find a certain instance of 

 this, except Hippophae, already mentioned under 

 Monoeda Tetrandria. 



3. Trioecla. Of the only two genera which have 

 ever been placed here,, Ceratonia, Cavan. Ic. t. 113, 

 belongs to Pentandria Monogynia. Ficus is so 

 celebrated for the diversity of its flowers, as con- 

 nected with the history of vegetable impregnation, 

 see p. 256, that we are glad to take advantage of a 

 trifling difference in the calyx of the two florets, 

 (the barren one being most frequently three-cleft, 

 the fertile five-cleft,) to keep it here. 



All things being considered, this Class may be 

 thought scarcely worth retaining. Yet as we know 

 two or three genera entitled to a place in it, upon 

 principles which the analogy of the two preceding 

 Classes shows to be sound, we cannot tell but others 

 may exist in the unexplored parts of the globe. For 

 this reason, and for the uniformity of the system, I 

 would venture to preserve it. If the twenty-first and 

 twenty-second Classes should hereafter be reformed 

 by some judicious and experienced hand, according 

 to the principle I have suggested, of retaining in 

 them such genera only as have a permanent diffe- 



