32 Principles of Plant Culture. 
mination. It is henceforth not only useless, but is a posi- 
tive hindrance to germination, in many plants, as it must 
be torn assunder by the expanding plantlet. If we examine 
germinating seeds of the squash or pumpkin, watching the 
germination process through its different stages, we may 
discover that, in these plants, nature has made a special 
provision to assist the plantlet in escaping from the seed- 
case. As the hypocotyl curves downward, a projection or 
hook is formed on the side toward the seed, which holds the 
seed-case down while the seed-leaves are withdrawn from it. 
The action of this hook is shown in the accompanying fig- 
Fic. 6. Showing nature’s provision to enable the pumpkin plantlet to escape 
from the seed-case. In A,the hook on the hypocoty] is attached to the lower half 
of the seed-case. B shows the same after germination is farther advanced. A 
fully germinated pumpkin plantlet is shown at Fig. 7. 
ures. Occasionally, as shown in C, the point of the seed- 
case breaks, permitting the hook to slip off, and if the seed 
happens to be planted edgewise, or with the point downward, 
the hook often fails to catch the seed-case, as in D, and so 
the plantlet emerges from the soil without freeing itself 
