GERMINATION OF SEEDS 97 



bases into short or sometimes long stalks. In the castor- 

 bean and the squash, the cotyledons not only escape from 

 the testa, but become green and work like ordinary leaves 

 (Fig. 90). 



In corn, as in all the cereals, the embryo lies close against 

 one side of the seed so that it is completely exposed by the 

 splitting of the thin skin that covers it. In this case the 

 single cotyledon is never freely expanded, but remains as 

 an absorbing organ in contact with the starch-containing 

 endosperm, while the root grows in one direction, and the 

 stem, with its succession of unsheathing leaves, grows in the 

 other direction (Fig. 91). 



