298 ANALOGY OF SEPALS AND PETALS. 



coloured parts, which seem to spring at once from the flower- 

 stalk, without bracts or calyx. But, if they be examined, it 

 will be found that three of these arise lower down than the 

 others, and therefore partly enclose them ; so that these three are 

 to be regarded (in spite of their colour) as sepals of the calyx ; 

 and it may often be observed that, though coloured in their 

 interior, they are greenish outside, especially along their middle. 

 In the Fuchsia, a beautiful plant which may now be grown 

 with little difficulty in our gardens, though formerly considered 

 a rare exotic, the calyx is even more brightly coloured than the 

 corolla. This change of colour, however, by no means disproves 

 what has been said of the analogy between sepals and leaves ; 

 since, as formerly noticed, leaves themselves occasionally undergo 

 similar changes ; and the colouring principle seems to consist, in 

 all cases, of nearly the same substance, in different states of 

 chemical combination (. 386). Further, the calyx not unfre- 

 quently returns to the form of true leaves, in flowers in which 

 its regular appearance is very different; such irregular forma- 

 tions, which are termed monstrosities, are in this, as in many 

 other instances, very instructive to the Physiologist, in leading 

 him to the knowledge of the true character of organs, of which 

 the external form may have been greatly changed. 



459. Similar remarks may be made upon the real nature of 

 the petals of the Corolla. They are almost always coloured ; 

 but they still preserve their leafy structure, having cuticle, sto- 

 mata, parenchyma, and veins. It has been seen that, in the 

 Tulip and Lily tribe, there is no essential difference between the 

 sepals and petals ; what is true of the former, therefore, must be 

 also true of the latter. Further, in the Paeony, the transition 

 from the form of the sepal to that of the petal, is as gradual as 

 that from the ordinary leaf to the sepal. If we trace the por- 

 tions of the perianth from without inwards, we may observe 

 that the green leafy sepals are slowly changed, in the first place 

 by having their points and edges turned from green to pink, and 

 becoming more delicate in their structure ; next the inner side 

 is seen to be completely coloured, while the back is still greenish 

 in its centre ; and finally the whole is converted into an ordinary 



