BY D. MCALPINE. 621 



the whole, just as in a firm leaf when the cells are all turgid, but 

 strengthening rods are required as well. There are ten of these 

 curved supports, normally equidistant from each other, diverging 

 from the stalk at the base, and becoming united again at the top, 

 just beneath the eye. These strengthen the whole structure, like 

 so many curved ribs, and the various branches form lesser supports. 

 It will be observed that this system of strengthening is not merely 

 mechanical; it is also a living mechanism, which has to gi-ow and 

 expand according to the strain it has to bear. 



The growth of the core and of the flesh concurrently, requires 

 a nice adjustment of the various contributing factors. The 

 enlarging core is richly supplied with a fine network of vessels 

 for its own immediate use, and there are also branches stretching 

 from it at various angles, traversing the flesh, and firmly rooted 

 beneath the skin. As the flesh enlarges, these branches stretch 

 in unison with it, and they are so tightly stretched that they 

 i-esemble so many stays keeping the core in position. This is 

 shown in Fig.9, where some of the strands are dissected out, and 

 while serving as holdfasts, they also convey nourishment when 

 required. 



The skin is likewise a form of skeleton, giving firmness and 

 consistency to the entire fruit, although its main function is to 

 regulate transpiration. The thick-walled mother-cells of the 

 epidermis are divided by thinner walls into more or less quadri- 

 lateral daughter-cells, and the appearance presented by them has 

 given rise to the name of " window-cells "(Figs. 13, 14). The 

 rapid expansion of the surface is provided for, to keep pace with 

 the internal growth, by means of these window-shaped cells; for 

 although in uninterrupted contact with each other, when they 

 stretch, a new window is inserted between, and thus the super- 

 ficial area is increased. 



Vascular bundles in relation to the Seeds. 



That the vascular bundles are developed primarily in connec- 

 tion with the "core" comprising the carpels, and gradually spread 

 out into the fleshy receptacle is evident from various considera- 

 tions. When a coloured fluid is injected into the stalk of the 



