TSE BOOT. 



17 



many cases, as iu the seedling of Wheat, Flax, etc., 



these may be seen by 

 the unaided eye, appear- 

 ing as a woolly cover- 

 ing. The special office 

 of these is to absorb the 

 dissolved fi)od from the 

 soil. 



8. When a seed germi- 

 nates, it generally sends 

 * a single root {radAele, 



Pig. 3,r.rf.) downwards, which is called the primary root. 



This may continue to grow, and remain larger than any 



of its branches or side-roots which 



it sends out, and in this case it is 



called the main, or tap-root. 

 9. The tap-root, when not woody 



(as in shrubs and trees), may be- 

 come fleshy, that is, thickened, as, 



for example, in the Carrot, Turnip, 



etc. This is in consequence of a 



deposit of nourishment which has 



been elaborated or prepared in the 



green parts of the plant. When it fC 



is larger at the top, or where it joins JZ. 



the stem, and tapers gradually down- 

 wards, it is said to be conical (Fig. 



4); if it is turnip-shaped, that is, 



very large above, tapering abruptly, 



and becoming very slender below. 



Fig. 2. Portion of a root^ with root-hairs, highly magnified. Fig. 3 . The Bean in 

 different stages of germination : cat, cotyledons ; //, plumule ; r.d., radicle ; cau, 

 caulide ; ivs^ leaves. 

 2 



