SECT. IV. DECOMPOSITE ORGANS. 



origin of the several parts by tracing the several 

 parts of the fruit-stalk to their termination. In the 

 fruit-stalk he thought he could discover the pith, 

 the central tubes, spiral tubes, and tubes of the 

 bark, together with its epidermis : and in tracing 

 them to their termination he thought the pith 

 seemed to end in the pistils ; the central vessels in 

 the stamens, after diverging round the core and ap- 

 proaching again in the eye of the fruit ; and the 

 bark and epidermis, in the two external skins.* 

 Hence he infers that the flower is a prolongation of 

 the pith, wood, and bark in nearly the same way as 

 Linnaeus, though he adduces arguments from dis- 

 section with which Linnaeus was not acquainted. 

 But although central vessels are found in the stamens, 

 it is no proof that the stamens are a prolongation of 

 the wood, unless the central vessels of the fruit-stalk 

 and common tubes of the alburnum are proved to be 

 one and the same, which remains yet to be done. 

 It seems also doubtful whether the fruit-stalk con- 

 tains any thing that can be absolutely regarded as 

 pith ; and it is evident from a very little inspection 

 -that the two external skins of the Apple are not verv 

 well accounted for by deriving them from the bark 

 and epidermis of the fruit-stalk. 



But another question of some considerable im- Nourish- 

 portance has arisen out of this subject : does the ^"flowe 

 flower or fruit elaborate sap for its own developement, and fruit * 

 or is it supplied with nourishment from the leaf? 

 * Phil. Trans. 1801. 



