CHAPTER II. 



NUTRITION (continued). THE MACHINERY. 



Boots : their nature. Koot-cap. Root-hairs. Root action. Absorp- 

 tion. Leaves and leaf action. Chlorophyll. Absorption of fluid and 

 gases. Leaf work by day and by night. Oxidation and De-oxidation. 

 Carnivorous plants. Transpiration. Circumstances propitious to 

 it. The Stem and its work. Its characteristics and varieties. Buds. 

 Branches. Tubers. Bulbs. Uses of the stem. Ascent of liquids. 

 Sap currents. 



Boots : their Nature, &c. So far as regards the absorp- 

 tion of those food materials derived from the soil by the 

 means above-mentioned, the root and its sub-divisions are 

 the agents through which the absorption takes place. It 

 is not necessary to allude to the various forms and modifi- 

 cations of roots which form the study of the botanist 

 further than to say that their manifold differences of form 

 depend chiefly on the relative proportion that the body of 

 the root bears to its branches. If, as in a " tap root," like 

 a carrot, the body is large, the branches are small ; if, as 

 in the "fibrous root" of a grass, the body is small, the 

 branches are numerous and long. 



In ordinary language a great many things are called 

 roots which are not strictly so. For most people all parts 

 of the plant situate below the surface of the gromv 

 roots or portions of roots. Botanists, having re 

 to the origin, mode of growth, structure, arid uses of roots, 

 are enabled to define roots partly by positive, partly by 



