10 VITAL ACTIONS. 



elevation of temperature, all the parts enlarge, and 

 new parts are created, at the expense of a mucilagi- 

 nous saccharine secretion which the germinating seed 

 possesses the power of forming. With the assistance 

 of this substance, the root, technically called the radi- 

 cle, at first a mere point, or rather rounded cone, 

 extends and pierces the earth in search of food ; the 

 young stem rises and unfolds its cotyledons, or rudi- 

 mentary leaves, which, if they are exposed to light, 

 decompose carbonic acid, fi.x the carbon, become 

 green, and, by processes hereafter to be explained, 

 when speaking of leaves, form the matter by which 

 all the pre-existing parts are solidified. And thus a 

 plant is born into the world ; its first act having been 

 to deprive itself of a principle (carbon) which, in 

 superabundance, prevents its growth ; but, in some 

 other proportion, is essential to its existence. 



CHAPTER II. 



GROWTH BY THE ROOT. 



Roots lengthen at their Points only. — Absorb at that Part 

 chiefly. — Increase in Diameter like Stems. — Their 

 Origin. — Are feeding Organs. — Without much Power 

 of selecting their Food. — Nature of the latter. — May be 

 poisoned. — Are constantly in Action. — Sometimes 

 poison the Soil in which they grow. — Have no buds. — 

 But may generate them. 



19. The root, being the organ through which food 



