Ch. XVT.] GERMINATION. 99 
411. The radicle, or 
descending root, is usu- 
ally first to break through 
the coats of the seeds; 
it commences its journey 
. downward, to seek in th 
, earth nourishment for the 
‘ future plant, and to fix it 
firmly in the earth. This 
constitutes the root, and 
always takes a down- 
ward course, in whatever 
situation the seed may 
have been placed in the 
ground. 
412. A botanist plant- 
ed in a pot, six acorns, 
with the points of their 
embryos upwards. At the 
end of two months upon 
removing the earth, he 
found that all the radi- 
cles had made an angle 
in order to reach down- 
wards. It is supposed that if the root met with no obstruction 
in going downwards, it would always be perfectly straight. 
Fig. 68. 413. Fig. 68 is the representation 
of a germinating seed of the Four 
o’clock; it will be seen that the radicle, 
a, has made nearly a right angle in 
turning downwards; the plume is not 
developed. 
a 414. If you put into a tumbler of wa- 
_ ter some cotton, and place upon it some 
seeds of rice or wheat, you will see all 
the fibres shooting from the seeds, in a 
perpendicular direction, downwards. It is a very simple and 
interesting experiment. Some ascribe this phenomenon to the 
laws of gravitation, by which the root is attracted towards’ the 
centre of the earth; others say that the radicle, stimulated by 
moisture, naturally extends itself in the direction from wiih 
411. What direction does the radicle take? 
412, What experiment did a botanist make with acorns ? 
413. What does Fig. 68 represent ? 
414. What experiment is mentioned, and what are some of the 
canses assioned far the downward eourse of the radicle 2 
