; eI NATION. 3. | D 
plumule depends, amongst other things, on the time of year. 
In a bean grown in damp air in November, the radicle did 
not burst through the testa 
until the third day from the 
time it was first soaked; in 
spring, the process would be 
much more rapid. 
Growth of 
Embryo. having burst the 
testa, grows downwards, 
giving off branches laterally, 
whilst the plumule is pushed 
out from between the cotyle- 
dons owing to the growth in 
length of their stalks. The 
main root which arises from 
the radicle is the primary 
root; its branches are lateral 
roots. : 
Structure of With the ger- 
Grain of mination of a 
Maize. bean seed may 
be compared that of maize. 
A grain of maize is not merely 
a seed ; it is the seed and the 
seed-vessel, so that it answers 
not only to the seed of the 
bean, but to the seed and the 
The radicle, 


Fig. 8.—BEAN SEEDLING. 
t, testa ; stk, stalk of cotyledon ; 
rt, primary root ; dat, lateral roots ; 
rh, root-hairs ; , plumule. 
pod. Its seed-coat has become united to its seed-vessel; the 
skin of the grain of maize, therefore, represents testa and seed- 
vessel. 
A grain of maize is rather longer than it is broad ; at the 
pointed end may be observed the rough edge, by which it 
was attached to the cob; the two broad surfaces are smooth, 
but. in the centre of one of them a greyish line is visible. This 
denotes the position of plumule and radicle. Round that is a 
shield-like, white substance, called from its shape the scutellum 
1—2 
