THE FRUIT AND THE SEED 301 
that seeds are fully matured. Immature seeds frequently do 
not germinate, or, if they do germinate, often produce weak 
seedlings. The age of the seed is also important. Many seeds, 
as we have seen, necessarily undergo a period of rest, and so 
can be stored for a considerable length of time without injury ; 

Fig. 306. Successive stages in the germination of squash 
Note the peg which catches into the seed coat and holds it while the cotyledons 
are pulled out. In the seed the cotyledons store food, during germination they 
supply food to the embryo, and later they serve as green leaves. (x +) 
but while seeds are apparently inactive, life processes are still 
going on, even though at a slow rate. If the seeds are stored 
for too long a time, they begin to lose their vitality; and this 
process, once started, continues until the seeds reach such a 
condition that they will no longer germinate. 
Germination. ‘The principal processes taking place during 
germination are the transfer of materials and growth. If. the 
reserve food is stored in the cotyledons, it is transferred to the 
growing plumule and radicle (Fig. 302). When food is stored 
in the endosperm it is first absorbed by the cotyledons and then 
conveyed to the regions of growth (Fig. 303). During germi- 
nation the cotyledon may therefore serve for the storage of 
