162 INTRODUCTION TO BOTANY 
153. Rest period before germination. A few kinds of seeds 
may sprout as soon as they are ripe; most kinds need a period 
of rest and comparative dryness before they will grow. The 
Fic. 144. Seed and seedlings of morning-glory 
A, section of seed, showing cotyledons folded together and inclosed in endosperm ; 
B, seed germinating, the taproot descending and the cotyledons pushed up out of 
the ground; (’, seedling with cotyledons expanded, the plumule showing as a 
bud at the junction of their leafstalks; D, seedling further developed; cot, coty- 
ledons; /, first ordinary leaf; l’, second ordinary leaf 
importance of drying seeds is well shown in the case of corn. 
Kiln-dried corn has, in one instance, been shown to yield sixteen 
bushels per acre more than air-dried seed of the same variety. 
