CHAPTER XXXI. 



THE FRUIT OF ANGIOSPERMS MUCILAGES DEVELOPMENT 

 OF THE FLOWER. 



MATERIALS USED. 



Ripe Plum or Cherry. Ripe Apple. Ripe Orange. All fresh. 

 Young inflorescences of Brassica Nfipiis, the Rape ; fresh. 



REAGENT USED. 



Potash. 



ONE of the simplest possible fruits, the achene of Alisma Plantago, 

 we have already become acquainted with ; as also the almost equally 

 simple caryopsis of the wheat. We will now take one or two cases 

 in which special modifications in development lead to ultimate 

 complexity of structure. 



The Plum or Cherry. A ripe plum, Primus domestica, using 

 any firm-fleshed kind, shows upon its surface a delicate covering 

 of wax, the so-called " bloom," which, in a surface section of the 

 epidermis, appears as a finely- granular covering. The same section 

 shows the epidermis composed of cells, which are arranged into 

 groups, and thus betray their origin from common mother-cells. 

 They contain rose-red cell-sap. A delicate cross-section shows us 

 under the epidermis some layers of cells rapidly increasing in size, 

 and, farther in, cells which are all uniformly large. These are 

 rounded off from one another, but form only small intercellular 

 spaces. They contain very small, scattered, yellowish-green 

 chlorophyll grains, a thin peripheral layer of protoplasm, a nuc- 

 leus, and colourless cell-sap. This parenchymatous tissue is 

 traversed by numerous branching vascular bundles, and towards 

 the stone the cells become smaller, radially elongated. The stone 

 itself, which, in order not to chip the razor, must be cut with the 

 greatest possible care, attempting very small sections only, and on 

 a surface previously prepared with a strong pocket-knife, consists 



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