LBCT. V.] THE ROOT. 207 



from the soil as can pass through the pores of the 

 epidermis, and conduct it to the caudex, or main 

 root, through the vessels of which it ascends to 

 the leaves : there it is as it were digested ; and, 

 being changed in its properties, is again conveyed 

 by another set of vessels to the caudex,, in which 

 it is deposited for the future exigencies of the 

 plant. As a proof that the fibrils are the only 

 parts of the root which take up the nutriment of 

 the plant from the soil, Mirbel remarks, that 

 " herbs perish at the foot of young trees, because 

 the fibrils issuing from the collet (the point of 

 connexion of the stem and the root) exhaust the 

 ground ; but old trees extending their vigorous 

 roots to a distance, allow the plants, which are 

 close 'to them, to subsist and destroy those which 

 are more distant." It has not yet been ascertained 

 whether the fibrils are strictly annual productions, 

 an opinion which was maintained by Du Hamel *, 

 Mirbel -f^, and Sir J. E. Smith;}:, and adopted by 

 Wildenow ; but which is doubted by Mr. Knight, 

 who, although he admits that in roots of trees, 

 or ligneous plants, crowded together in a garden- 

 pot, the fibrils are often found lifeless in the suc- 

 ceeding spring ; yet, remarks that he has "not 



* Phys. des Arores. 



j- Traite d'Anatomie. 



J Introd. to pkysiol.and system. Botany. 



Principles of Botany , Eng. trans. 260. 



