GERMINATION 



13 



is absorbed and passed on to the other parts of the seed. The 

 taking in of water causes both embryo and surrounding food (en- 

 dosperm) to swell and the seed coat to crack lengthwise. The 

 appearance of the radicle through or near the hiluin is again 



/Si. 



FIG. 7. Different stages in the germination of the squash. 



our first evidence of germination, followed by the elongation 

 of the hypocotyl and the lifting of the cotyledons above the sur- 

 face of the soil very much as in the case of the bean. How- 

 ever, the seed coats persist much longer than in the bean and the 



FIG. 8. Bean seedling coming through the soil. 



food is gradually absorbed by the cotyledons. As the food dis- 

 appears the cotyledons gradually become green and leaf-like in 

 appearance and function. They usually fall early, but are 

 sometimes retained for a long time. 



