208 FLORAL ENVELOPES. [BOOK n. 



CHAPTER VIII. 



OF THE BRACTS AND FLORAL ENVELOPES. DISENGAGEMENT 



OF CALORIC. 



THE bracts, when but slightly different in colour and form 

 from leaves, no doubt perform functions similar to those 

 of the latter organs ; and, when coloured and petaloid, it may 

 be presumed that they perform the same office as the corolla. 

 Nothing, therefore, need be said of them separately. 



With regard to the calyx, corolla, and disc, I chiefly 

 follow DunaPs statements in his ingenious pamphlet, Sur les 

 Fonctions des Organes floraux colores et glanduleux : 4to > 

 Paris, 1829. 



The calyx seems, when green, to perform the functions of 

 leaves, and to serve as a protection to the petals and sexual 

 organs ; when coloured, its office is undoubtedly the same as 

 that of the corolla. 



The common notion of the use of the corolla is, that, inde- 

 pendently of its ornamental appearance, it is a protection to 

 the organs of fertilisation ; but, if it is considered that the 

 stamens and pistils have often acquired consistence enough to 

 be able to dispense with protection before the petals are enough 

 developed to defend them, it will become more probable that 

 the protecting property of the petals, if any, is of secondary 

 importance only. 



Among the many speculations to which these beautiful 

 ornaments have given birth is one, that the petals and disc 

 are the agents of a secretion which is destined to the nutrition 

 of the anthers and young ovules. These parts are formed in 

 the flower-bud long before they are finally called into action ; 

 in the Almond, for example, they are visible some time before 

 the spring, beneath whose influence they are destined to 



