COTYLEDONS. 



621 



With regard to the forms assumed by the cotyledons now withdrawn from the 

 seed under favourable conditions, and which have become green in the sunlight, it is 

 to be noticed that they present far fewer variations than those of ordinary foliage- 

 leaves. Usually their margins are entire, their form elliptical or linear, more 

 rarely circular and obovate. Sometimes the cotyledons are indented in front, 

 resembling a heart in outline; this is especially the case where the embryo is folded 



^-f^ 



Fig. 148.— Cotyledons. 



2, 3 Fagus sylvatica. * Fumaria officinalis. * Galeopsis pubescens. « Abies orientalis. i Convolvulus aroensis. 

 officinalis. ^Senecio eruemfolius. ^o Mosa canina. ^^ Erodium Cicutarium. ^i Quamoclit coccinea. ^* Tilia grandijolia. 

 11 Lepidium sativum. 16 Eucalyptus orientalis. is Eucalyptus coriaceus. I'-^o Streptocarpus Rexii. 



in the seed, so that the radicle lies close to the outer margin of the cotyledons, and 

 may be explained as an economy of the scanty space within the seed. Most rarely 

 of all the cotyledons are two-lobed (Raphanus sativus), and bisected (Eucalyptus 

 orientalis, Eschscholtzia Californica), three-lobed {Erodium Cicutarium), and tri- 

 sected (Lepidium sativum), four-lobed (Pterocarya Caucasica), and five-lobed 

 (Tilia). It is still to be mentioned that in all seedlings whose hypocotyl is short, 

 the blade of the cotyledons has a long stalk, while in seedlings with elongated 

 hypocotyls the blade is sessile. This is connected with the processes already 

 mentioned, and also partly with the fact that it is of importance to seedlings that 



