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A TEXT-BOOK OF BOTANY 



posed that all of the details of germination given for the 

 garden bean are found in the germination of all seeds. The 

 conditions for germination, and such life processes as res- 

 piration, digestion, etc., belong to the germination of all 

 seeds; but the relations of parts to one another and the 



details of the es- 

 cape of the young 

 plantlet vary wide- 

 ly, and should be 

 examined in as 

 many plants as 

 possible. For ex- 

 ample, in the scar- 

 let-runner bean the 

 cotyledons are not 

 usually freed from 

 the testa, the first 

 internode of the 

 stem developing 

 the arch and free- 

 ing the leaves, as 

 may be seen in the 

 series shown in 

 Figs. 89 and 89a 

 which is completed 

 by Fig. 57. 



Seeds such as 

 peas, castor-bean, 

 squash, and corn 

 also should be ger- 

 minated, as they show important variations. For exam- 

 ple, in the pea and the acorn the cotyledons, so gorged 

 with food as to have lost all power of acting as leaves, 

 are never extricated from the testa; but the plumule is 

 pushed out by the elongation of the cotyledons at their 



FIG. 91. Seedling of corn at several stages, showing 

 the superficial position of the embryo, the unfold- 

 ing leaves, and the roots; the single cotyledon is 

 not seen, remaining in close contact with the endo- 

 sperm. 



