12 THE GROWTH AND PARTS OF PLANTS 

Fic. 22. Marrow seedlings casting the seed coats (note the ‘‘ peg ’’). 
stem a “peg” or “heel.” This is formed on the under- 
side of the stem, when the seed 1s lying on its side, at 
the point in the opening of 
the seed. This peg presses 
against the end and helps to 
split the seed coat further 
open. The stem now elon- 
gates above this peg, presses 
against the other half of th 
seed coat, and prises the two = 
halves far apart so that the 


Fic. 23. Bean seeds ger- 
minating under glass. 
plant readily slips out, as shown 
in Fig. 22. 
Germination of the bean. After 
the root comes out of the bean 

On the: Go heave Fig. 24. Peas germinating 
under glass. 
side, the two halves 
ny ae of the bean swell so that the outer coat 
seed germinating. iS cracked and begins to slip off. We can 
oa 

