656 



THE FIBRO-VASCULAR SYSTEM OF THE PEAR 



(POME). 



By D. McAlpine, Corresponding Member. 

 (Plates xxvi.-xxix.) 



I have already dealt in some detail with the vascular system of 

 the apple {antea, p.613), and it is so closely related to that of the 

 pear, that it will not be necessary to treat the latter with the 

 same degree of fulness. 



The fruits of the apple, pear, and quince, known as Pomes or 

 Pip-fruits, are characterised by possessing five carpels, constituting 

 the "core" or true fruit, and surrounded by a fleshy portion 

 generally considered to be the swollen and succulent receptacle. 

 The pulpy flesh of the pear and quince differs from that of the 

 apple, however, in containing groups of what are known as 

 "stone-cells" scattered among the thin- walled cells of the 

 parenchymatous tissue. These constitute the "grit" of the pear 

 and quince, and consist of cells with strongly thickened, lignified 

 walls, hence called sclerenchyma. 



Transverse and longitudinal Sections of Pear. 



If a thin transverse section of the peai* is made through the 

 core, and phloroglucin used as a stain, followed by hydrochloric 

 acid, the stone-cells turn a bright red colour; and while seen to 

 be scattered through the flesh, extending even to the skin, they 

 are densely clustered around the core(Fig.2). The pear likewise 

 difiers from the apple in being more or less top-shaped, so that 

 the carpels are relatively nearer the crown or blossom-end, and 

 not so central because there is a much larger pi'oportion of the 

 fruit representing the receptacular portion beneath the core(Fig.4). 

 On this account, the primary vascular bundles are seen traversing 

 the flesh for a greater portion of their course than in the apple, 

 and a better insight is thereby gained into their relative positions 

 before they reach the carpels. 



