CYCADALES 



147 



of red and orange predominating. Beneath the fleshy layer is a hard, 

 tough, stony layer; and, within this, the inner, fleshy layer, which 



Fig. 162. — Dioon edule: early cotyledon stage of embryo; the enlarged portion back 

 of the cotyledons is the coleorhiza; periclines show that the dermatogen is not yet fully 

 differentiated. — After Chamberlain.'"* 



soon gives up most of the cell contents to the 

 female gametophyte and growing embryo. 

 This layer, containing the inner vascular sys- 

 tem, becomes a dry, papery membrane. Just 

 underneath the top of it the remains of the nu- 

 cellus can be seen, forming a dry, papery cap. 

 The embryo, now extending the whole length 

 of the seed, inside the seed coats, has two cot- 

 yledons, which are not always equal in size; 

 one leaf with usually one or more scale leaves ; 

 and the long suspensor coiled and packed 

 against the micropylar end. 



Fig. 163. — Ceratoza- 

 mia mexicana: young 

 embryos with suspen- 

 sors; the rounded bodies 

 at the top are the tough 

 egg membranes; Xi.S. 

 —After Chamberlain.'" 



