ANGIOSPERMS. DICOTYLEDONS. 



449 



Thick fleshy cotyledons usually remain in the seed during germination, and perish 

 when all their food-material has been withdrawn from them, as in Phaseolus multi- 

 florus, Vicia Faba (Fig. 376), and Quercus (Fig. 379) ; in this case the stalks of the 

 cotyledons elongate so much, that the plumule between them is pushed out of the seed 

 (Fig. 379) and then grows erect, so that the seed-coat with the cotyledons looks like a 

 lateral appendage of the axis of the embryo. But usually the cotyledons, especially if 



FIG. 379. Quercus robur. I longitudinal section of the embryo mag- 

 nified, after removal of the anterior half of both cotyledons c c ; the hypo- 

 cotyl he, the primary root TV and the plumule b are enclosed between the 

 basal portions of the thick cotyledons, st stalk of the cotyledons. // com- 

 mencement of germination ; the pericarp and one cotyledon have been re. 

 moved, and the hypocotyl and the root have lengthened (natural size). 

 /// germination in a more advanced stage after the plumule b has issued from 

 the seed-coat sh and the pericarp s by the elongation of the stalks of the 

 cotyledons ; -uS its secondary roots. The letters in // and ///as in /. 



FIG. 380. Almond germinating ; one of the 

 cotyledons c> c? dividing ; the letters as in figure 

 379 ; * the first internode very strongly developed. 



they are thin, are destined to further development and form the first foliage-leaves of the 

 plant ; in order to liberate them and the plumule that lies between them from the seed, 

 the hypocotyl lengthens considerably, forming thereby at first a curve convex upwards 

 (Fig. 375), because the cotyledons are still detained in the seed while its lower end is 

 fixed in the ground by the root ; but ultimately a final elongation of its lower portion 

 0] Gg 



