96 LABORATORY MANUAL 



of seeds just beginning to sprout. Review the parts 

 of the embryo in Exercise 62. What part of the 

 embryo emerges first from the seed coat? At what 

 point does it come through? Into what part of the 

 mature plant does it develop? Make a sketch to show 

 these points. 



B. To determine one of the functions of a cotyledon, 

 set up the following experiment : 



Fill a wide mouth bottle with water. Cover the 

 mouth of the bottle with mosquito netting. Choose 

 four young seedlings of about the same size each of 

 corn, pea, and lupine. From two of each kind care- 

 fully remove the cotyledons. Then suspend all the 

 seedlings from the netting with the roots projecting 

 into the water. After a week make observations on 

 the growth of the seedlings with cotyledons, and com- 

 pare with the growth of those from which the coty- 

 ledons were removed. 



C. Methods of emerging from the soil. 



In a pot of germinating seeds of the castor bean, 

 squash or lima bean, and corn, or any other grain, 

 make observations on various stages of the growth of 

 the seedlings. In the castor bean, squash, or lima bean, 

 what part of the seedling emerges from the soil first? 

 In what manner does it come above the surface? Of 

 what advantage is this method to the seedling? Does 

 the arch persist after the cotyledons and plumule are 

 above the surface ? 



Sketch at least three stages in the above develop- 



