SEED AND ROOT 



177 



make the process plainer, 

 the disc at the] end of the 

 radicle adheres very 

 tightly to whatever it is 

 applied to : the radicle 

 itself straiglitens, and 

 tears away the viscid 

 berry from whatever it 

 has adhered to, and raises 

 it in the air. The radicle 

 then again curves, and 

 the berry is carried by it 

 to another spot, where it 

 adheres again. The disc 

 then releases itself, and 

 by the curving about of 

 the radicle is advanced to 

 another spot, where it 

 again fixes itself. This, 

 Dr. Watt says, has been 

 repeated several times, so 

 that to a certain extent 

 the young embryo, still 

 within the seed, moves 

 about. It seems to select 

 certain places in prefer- 

 ence to others, particularly 

 leaves. The berries on 

 falling are almost certain 

 to alight upon leaves, and 

 although many germinate 

 there, they have been observed to move from the leaves to the stem, and 

 finally fasten there " (Gardener's Chronicle, 1881). 



Though the direction of the roots is normally downwards, it would appear 

 from experiments begun by Colonel Greenwood more than fifty years ago 

 that they will grow in any direction in which they can find food. The 

 colonel placed a number of Horse-chestnut seeds in flower-pots, which he 

 suspended in an inverted position on wirework, and watered the seeds from 

 above. The main-root which each seed sent down into the air presently 

 died ; but the branch-roots, which had not taken a downward course, continued 

 to grow, and the plants nourished. He had thus stumbled upon the fact that 

 the seedlings of the Horse-chestnut have a primary root whose downward 

 determination nothing can pervert. This downward root is as peculiar to 

 the seedling as the seed-leaves are, but the branch-roots will grow in any 

 15 



Photo by] [E. Step. 



FIG. 221. WILD CAKROT (Daucus carota). 



One of the most graceful of the smaller Umbelliferous plants. From its 



hard, dry, stick-like roots the thick, fleshy garden-carrots have been evolved 



by cultivation. EUROPE, X. AFRICA, N. ASIA. 



