344 OKGANOGKAPHY. 



of form, &c., which the different parts of plants undergo in 

 order to adapt them to the several purposes for which they were 

 designed, we proceed to prove that all the parts of a flower are 

 homologous with leaves. In doing so, we shall examine the several 

 parts of the flower, both as they exist in a natural condition, 

 and in an abnormal state, commencing with the bract, and then 

 proceeding in a regular manner with the different whorls of which 

 it is composed, according to their arrangement from "vvithout 

 inwards. 



That the bract is closely allied to the leaf, is evident from its 

 structure, form, colour, and from the ordinary development of 

 one or more buds in its axil. In order to be perfectly convinced 

 of this analogy, let any one examine the Foxglove, the Lilac, or 

 the Pseony, and then it will be evident that all stages of transi- 

 tion occur between leaves and bracts, so that it will be impos- 

 sible to doubt their being homologous parts. 



That the sepals are homologous with leaves, is proved, not only 

 by their colour, &c., but also by the fact, that many flowers ex- 

 hibit in a natural condition a gradual transition between sepals 

 and bracts, and the latter, as already noticed, are readily re- 

 ferrible to the leaf as a type. Thus in the Camellia, the transi- 

 tion between the sepals and bracts is so marked, that it is 

 almost impossible to say where the latter end and the former 

 begin. In the Marsh Mallow {fig. 369), and Strawberry {fig. 

 370) again, the five sepals in the flowers of the two respectively 

 alternate with five bracts, and the difficulty of distinguishing 

 them is so great, that some botanists call both sets of organs by 

 the name of sepals. In many flowers in a natural condition, 

 therefore, there is a striking resemblance between sepals and 

 leaves ; and this analogy is at once proved to demonstration by 

 the fact, that in monstrous flowers 

 of the Eose, Clover, Primrose {fig. 

 764), &c., the sepals are frequently 

 converted into true leaves. 



We now pass to the jpetals, and 

 altliough these in the majority of 

 flowers are of a different colour 

 to leaves and the parts of the 

 flower which are placed external to 

 them, yet in their flattened charac- 

 ter and structure they are essentially 

 the same ; and their analogy to leaves 

 is also proved in many natural floM^- 

 Fig. 764. Monstrous Primrose, ers by the gradual transitions exhi- 

 tTue^eavll'''IX"LSi'." l>ited between them and the sepals. 

 This is remarkably the case in the 

 White Water-Lily {fig. 436) ; also in the Magnolia, Calycan- 

 thus, &c., where tha flowers present several whorls of floral 



