ANATOMY AND PHYSIOLOGY OF PLANTS. 231 



attached to the ground or to the substance on which 

 they feed ; we find they all agree in being fibrous at 

 their extremities, and it is by these fibres chiefly, that 

 they are fitted to draw nourishment. 



All parts of the root possess the power of emitting rootlets or 

 fibres when they are placed in favourable circumstances ; which 

 fiibres are made up chiefly of the ligneous texture of the stem. 



8. The fibres are therefore, the organs which absorb 

 nutriment from the earth, and convey it to the larger 

 root, by which it is transmitted to the plant itself. 



Hence, as DnHamel observed, the earth is exhausted of its nutri- 

 ent matter, chiefly where these capillary fibres are distributed, and 

 not in the neighbourhood of the larger roots. 



9. According to Du Hainel, the natural direction of 

 most roots is the perpendicular ; but if they meet with 

 any obstacle, they then take an horizontal direction, not 

 by the bending of the original shoot, but by the sending 

 out of lateral shoots. The same effect also follows, if 

 the extremity of the root is cut off. 



Du Hamel made some cherry-stones, almonds and acorns to ger- 

 minate in wet sponge; and when the roots had grown to the length 

 of two inches, he then placed them in glasses as bulbous roots are 

 placed, so that the extremity of the root touched the water. Some 

 were previously shortened by the cutting off of a small piece from 

 the 'point ; others were put in entire. The former sent out lateral 

 shoots, but elongated no farther in a perpendicular direction ; the 

 latter descended perpendicularly to the bottom of the glass. He cut 

 off also the tips of some roots vegetating in the earth, and had the 

 same result ; the wound cicatrized, and the root sent out lateral 

 divisions. 



10. The same phytologist also made many obser- 



