NATURAL CLASSIFICATION. 



131 



that the radicle is directed upwards or downwards, it is the 

 same thing as if we said, that the seed stands upright, or hangs, 

 in relation to the fruit, downwards; (121.) Properly, there- 

 fore, this character has a reference, not to the situation of 

 the embryon, but to the situation of the seed, and its value is 

 not of the first but of the second rank. 



The situation of the parts of the flower must always be re- 

 ferred to the receptacle, because they arise from it. But it 

 is often very difficult to determine the true position of these 

 parts on the receptacle ; and we sometimes only conjecture it 

 from the mutual junctions which take place, because we na- 

 turally take for granted, that organs stand nearer to one an- 

 other at their origin, the greater disposition they shew to 

 imite together. 



196. 



Still more important than their absolute situation is the po- 

 sition of different organs with respect to one another. We 

 must not only know that the filaments stand on the recepta- 

 cle, but also, whether they alternate with the petals, or are 

 set opposite to them, and stand before them. Especially, it 

 is of much consequence to consider the position of the parts 

 of the corolla and calyx with respect to each other, because in 

 this matter Nature preserves a very particular regularity. 

 The most usual case, is that in which the filaments stand be- 

 fore the parts of the calyx, and alternate with the petals 

 and with the loculi of the fruit. There is no kn«3wn in- 

 stance, however, in which the loculi of the fruit, the fila- 

 ments, and the parts of the corolla and calyx, all stand di- 

 rectly before or behind one another. The instances are rare 

 in which the parts of the corolla and calyx stand before one 

 another, and the filaments alternate with them ; or in which 

 the filaments, and the parts of the corolla, stand before one 

 another, and alternate with the parts of the calyx. The po- 

 sition of the stem-leaves also depends on the same principles. 

 The alternate position of the leaves is peculiar originally to 

 the imperfect and albuminous plants, — the opposite and 



IS 



