184 



PLANT STEUCTURES 



known as the seed coat, or testa (Fig. 153a). The devel- 

 opment of this testa hermetically seals the structures with- 

 in, further development and activity 

 are checked, and the living cells pass 

 into the resting condition. This pro- 

 tected structure with its dormant cells 

 is the seed. 



In a certain sense the seed is a transformed ovule (mega^ 

 sporangium), but this is true only as to its outer configura- 



FiG. 153a. Pine seed. 



Fig. 154. Pine aeedlinf^s, ehowing the ](»ng hypocotyl and the numerous cotyledons, 

 with the uld seed case still attached. — After Atkinson. 



