CHAPTER III 



MOVEMENTS, DEVELOPMENT, AND MORPHOLOGY OF 

 THE SEEDLING 



32. How the Seedling breaks Ground. As the student 

 has already learned by his own observations, the seedling 

 does not always push its way straight out of the ground. 

 Corn, like all the other grains and grasses, it is true, sends 

 a tightly rolled, pointed leaf vertically upward into the 

 air. But the other seedlings examined usually will not 

 be found to do anything of the sort. The squash seedling 

 is a good one in which to study what may 

 be called the arched hypocotyl 

 type of germination. If the co 

 seed when planted is laid hori- 



M 



A BCD K 



FIG. 9. Successive Stages in the Life History of the Squash Seedling. 



GG, the surface of the ground ; r, primary root ; r', secondary root ; c, hypocotyl ; 

 a, arch of hypocotyl ; co, cotyledons . 



zontally on one of its broad surfaces, it usually goes through 

 some such changes of position as are shown in Fig. y. 



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