58 WILSON & TOOMER FERTILIZER COMPANY 



its water content. Cut a succulent branch, and how soon 

 it becomes limp and wilted ! Plants cannot carry on the 

 process of growing without sufficient water content, as 

 all cells must be properly extended, and, too, water must 

 be the carrier of all substances within the plant. 



How Plants Feed There are no openings into the 

 roots, nor from cell to cell ; all plant food, whether in 

 raw or digested state, being moved in solution by osmosis 

 and diffusion. Osmosis means the passing of liquids or 

 gases through a membrane in accordance to Nature's law 

 that the density of the divided substances be equalized. 

 Diffusion means the "spreading out" of each particular 

 substance in solution to make the solution of that sub- 

 stance of equal strength throughout. Much has been said 

 about the plant's "power to select," but the best author- 

 ities now agree in the opinion that roots have no power 

 to reject anything dissolved in the soil water, regardless 

 of how harmful it may be to the plant. However, plants 

 grow according to definite law, each plant developing 

 along the lines of its own particular family. Soil solu- 

 tions are very dilute. Normally, the plant sap is denser 

 than the soil water, though the sap seldom is heavier 

 than one pound of solid matter to sixty gallons of water. 

 While osmosis causes the more dilute solution to move to 

 the denser one, diffusion tends to equalize throughout the 

 solution the amount of each substance dissolved. The 

 leaves (and in a lesser degree all live plant surfaces) are 

 constantly giving off water a process similar to evapora- 

 tion, but called "transpiration." This tends to concen- 



