112 



SEEDS AND SEEDLINGS 



any advantage in their being dragged out of the ground 

 backwards in this way rather than 

 pushed up tip foremost ? What 

 changes have the cotyledons under- 

 gone in the successive seedlings ? 

 Remove from the earth a seedling 

 just beginning to sprout and sketch 

 it. From what point does the hypo- 

 cotyl protrude through the coats ? 

 Does this agree with its position as 

 sketched in your study of the seed ? 

 In which part of the embryo does 

 the first growth seem to have taken 

 pkce ? 



Remove in succession the several 

 seedlings you have sketched and 

 note their changes. How does the 

 root differ from that of the corn 

 and oats ? Look for root hairs ; if 

 there are any, where do they occur .'' Mark off the root of a 

 young seedling into sections as directed in Section 148, and 



247. — Seedlings of bean in 

 different stages of growth : cc, 

 cotyledons, showing the plu- 

 mule and hypocotyl before 

 germination ; a, b, d, and tf, 

 successive stages of advance- 

 ment. At d the arch of the 

 hypocotyl is beginning to 

 straighten ; at « it has entirely 

 erected itself. 



249 



248, 249. — Root of bean seedling, 

 measured to show region of growth : 

 248, early stage of germination; 249, 

 later stage. 



250 251 



250, 251. — Stem of bean seedling, 

 measured to show region of growth : 

 250, early stage of growth; 251, later 

 stage. 



