PLANT PROPAGATION 



99 



7. Look at a pot of young seedlings that are just pushing 



their way above the surface of the soil or sawdust, 

 a. Which part of the embryo first appears above ground ? 

 6. What is the shape of this part ? 



8. Study a whole seedling at this stage (see 7 above), 



from which one cotyledon has been removed, 

 a. Describe the changes that have taken place in each 



part of the embryo since the seed began to sprout. 

 6. Describe the position and appearance of the main root 



and its branches that appear in this stage. 

 c. Make a drawing, natural size, of a seedling at this 



stage and show by a horizontal line the ground level. 



Label each part. 

 9. Study a well-developed seedling, comparing it with the 



stages already drawn, and answer the following 



questions : 

 a. What changes in the size of the cotyledons do you 



notice as the seedling grows older? Most of the 



food for the early development of the seedling is 



furnished by the cotyledons ; suggest, therefore, 



the cause of the change in size of the cotyledons, 



which you have noticed. 

 6. What parts of the developing embryo have changed in 



color during germination; how have they changed? 



B c 



FIG. 45. Stages in the development of the squash seedling. (Bailey.) 



