STRUCTURE OF SEED. 211 



the rest of the embryo, by a small circular hole, from 

 the envelope formed by the spermoderm invested with 

 the pericarp and calyx ; the other is very large, fari- 

 naceous, borne upon a long petiole, and remaining in the 

 spermoderm, the whole of which it fills ; the first, which 

 is rudimentary, is almost useless, and does not furnish 

 any nourishment ; the second provides the radicle with 

 all the nourishment which serves for its development ; 

 whence it results that the side of the root which cor- 

 responds to the great cotyledon increases much, and 

 gives rise to a great number of little roots ; whilst the 

 opposite side, which corresponds to the small cotyledon, 

 does not produce any little roots, and, as it remains 

 very short, draws towards it the whole body of the 

 root. 



The cotyledons, considered as to the manner in which 

 they are folded or rolled up in the seed, present as many 

 varieties as leaves in the bud ; considered as to the 

 position of the radicle, they are sometimes continuous 

 with it, as in erect embryos, and sometimes curved or 

 folded upon it, — a character which is more frequently, 

 but perhaps less correctly expressed, by saying that the 

 radicle is curved or folded upon the lobes. Dicotyledons 

 present two very evident varieties among folded em- 

 bryos ; thus, sometimes the radicle is folded back upon 

 the cotyledons, so as to he in the fissure between them ; 

 this is seen in all the Papilionaceous Leguminosa? and 

 Cruciferao Pleurorhizeae ; in this case we say that the 

 radicle is Lateral, which is indicated by the sign o=; 

 or the radicle is folded upon the back of one of the 

 cotyledons, and it is then said to be Dorsal, which is 

 expressed by the sign o|| : this is seen in the Cruciferao 

 Notorhizeae. 



If we consider the respective position of the cotyledons 

 themselves, we shall find several varieties : — 



p 2 



