348 ORGANIC CHEMISTRY. 



nel is tightly covered with a piece of blad- 

 der, and then filled with a solution of sugar 

 or salt. A tube is then fitted, air tight, to 

 its extremity. A glass vial, from which 

 the bottom has been removed, may be sub- 

 stituted for the funnel in this experiment. 

 On placing the apparatus, thus arranged, in a 

 vessel of water, the latter penetrates the ani- 

 mal membrane, and adds itself to the con- 

 tents of the funnel. The flow of the water 

 is called endosmose, and is made apprecia- 

 ble to the eye by the rise of liquid in the tube. An 

 cxosmose, or flow of a small portion of the contents of 

 the funnel outward, takes place at the same time. 



875. The phenomenon exhibited in the 



Explain the . 



phenomenon above experiment, is to be accounted for 

 of endosmose. by the difference of cap il] a ry attraction in 



the bladder for the two liquids. The spongioles, with 

 which the extremities of the roots are provided, being 

 filled with solutions of gum and sugar, act similarly 

 upon the liquids of the soil. The endosmotic action, 

 above described, is not confined to the roots of plants, 

 but occurs in all their organs, through the walls of the 

 minute cells of which they are composed. In connec- 

 tion with the transpiration of water from the leaves, 

 it is probably the principal cause of the circulation of 

 the sap. The relation of the plant and soil is further 

 considered in a subsequent chapter. 



876. CONSTITUENTS OF PLANTS. Amoner 



Mention some 



of the more the more important of vegetable substances 

 ffSe a ^ Ve ' are wood, starch, sugar and gluten. Woody 

 stances. fibre forms the mass of the plant ; starch 



