78 



SEEDS AND SEEDLINGS 



seedling, you will be able to obtain a complete record of the growth 

 of the kidney bean. The first signs of germination are the break- 



A series of early stages in the germination of a kidney bean. 



ing of the testa and the pushing outward of the hypocotyl to form 

 the first root. A little later the hypocotyl begins to curve down- 

 ward. A later stage shows the hypocotyl lifting the cotyledon 

 upward. In consequence the hypocotyl forms an arch, dragging 



after it the bulky cotyledons. 

 The stem, as soon as it is 

 released from the ground, 

 straightens out. From be- 

 tween the cotyledons the bud- 

 like plumule or epicot3'l grows 

 upward, forming the first true 

 leaves and all of the stem 

 above the cotyledons. As 

 growth continues, we notice 

 that the cotyledons become 

 smaller and smaller, until 

 eventually their food contents 

 having been absorbed into the 

 young plant, they dry up and 

 may fall off. The young 

 plant is now able to care for 



Bean seedlings. Note that in the older -x ir i i_ ■ i j. t_ 



seedlings at the left the eotyledons have '^^^'^ ^^^^ "^^^^ ^"^ ^^'^ *» ^^^^^ 

 been almost entirely used up. paSSed through the stages of 



