212 



GYMNOSPERMS 



regions, there is no organized suspensor. The further development of 

 the basal region is rapid, and soon there is a differentiation into stem, 

 root, and cotyledons (tig. 231 ^4, B). During their earlier develop- 



FiG. 229. — Ginkgo biloba: archegonium and embryo; A, top of archegonium, show- 

 ing the two neck cells; B, transverse section of the two neck cells; C, archegonium just 

 after the formation of the ventral canal cell {v) ; /;, nucleus of egj^s; D, free nuclear stage 

 of the embryo; E, the embryo has become cellular throughout; A and H, X 160; C, D, 

 and E, Xf)6. — After Strasburgkr.s»<' 



ment, one of the cotyledons is longer than the other and is notched 

 at the tip, while the shorter one is deeply cleft, recalling the bilobed 

 character of the foliage leaf. At maturity, the cotyledons are of 

 nearly equal length. Mucilage canals are abundant in the stem and 



