UNEQUAL COTYLEDONS 



31 



In the Mustard (fig. 3), Cabbage, Eadish (Raphanus), and 

 some other Crucifers, the difference is more marked, and is 



FIG. 02. Haphanus sativus. A, outline of seed, x 4 : m, micropyle ; 

 h, hiluin. B, embryo extracted from seed, x 4. C, embryo, x 4 ; 

 vertical section. D, embryo, seen from the side, x 4 : o.c, outer 

 cotyledon ; i.c, inner cotyledon ; r, radicle ; t, testa. E, germinating 

 seedling, x 2, showing the cotyledons still folded. 



due to a different cause. The cotyledons, as just mentioned, 

 are applied to one another face to face (fig. 62, B-D), and 



FIG. 63 Cereus Napoleonis. 

 Section of seed : oc, outer 

 coat of testa ; ic inner coat 

 of testa 



FIG. 64. A, embryo of Abronia arenaria, 

 x 6 : ic, smaller cotyledon. B, embryo 

 of A. umbellata, x 6: ic, right and inner 

 cotyledon ; Ic, left cotyledon 



then doubled longitudinally one inside the other. The outer 

 one, therefore, having more space, becomes larger and the 

 petiole is longer. In Cereus (fig. 63) the embryo is much 



