596 AGRICULTURE. 



more the sunshine, air, and gases had to do with making it, 

 than the soil. 



How Plants get Food from the Soil. Plants get food 

 from the soil by means of their roots, you will say. Of course 

 they do; but just how they do it has only been somewhat 

 definitely ascertained of late years. Formerly it was thought 

 that the tips of the roots were like sponges, and soaked the 

 water in just as a sponge does. But since we have gotten bet- 

 ter microscopes, we have found that the extreme tip of each 

 rootlet is a pointed cap of rather older material than that just 

 behind it, and that the new growth of the root is made just 

 behind this root-cap, in both directions, so that the outside of 

 the cap is of older and harder material, which is continually 

 being renewed as it wears in pressing through the soil. We 

 can see how important this arrangement is, in enabling a root 

 to make its way into the soil. If we get a young rootlet out of 

 the soil, without injury, and examine with a magnifying-glass of 

 good power, we will see, just behind the cap at the tip, that the 

 whole surface of the rootlet is covered with fine white hairs. 

 These are so fine that, in most plants, we cannot distinguish 

 them at all with the naked eye ; but these little root hairs are 

 the only means the plant has for getting the mineral matters 

 from the soil. We see, then, how important it is that the food 

 of the plant be completely dissolved in the water, for these 

 extremely fine hairs cannot take up anything of a solid nature. 

 The root hairs are only found on the youngest part of the fine 

 rootlets, and they soon dry off, while new ones are produced as 

 the root grows further, and they have fresh food presented to 

 them. The water taken up into the plant, charged with various 

 mineral foods, is brought in contact with the substances taken 

 by the leaves from the air, and thus all the combinations found 

 in plants are made. 



How Plants construct their Stems, Roots, and Branches. 

 The water taken up by the roots from the soil is simply crude, 

 undistinguished sap-water. This is taken rapidly up through 

 the sap-wood and pith, and taken where the wonderful labora- 

 tory of the leaves is in operation. The taking, of the carbon 

 from the air, by the leaves, is called assimilation, and from this 

 assimilated food, made into starch by the action of the water in 



