Dr. Smith's Inquiry into the Structure of Seeds. 209 



fold, exactly as happens to the subterraneous Cotyledons. The 

 same thing very often takes place as speedily in those which rise 

 out of the ground ; the existence of the latter appearing to be 

 prolonged in some instances, merely by their nearer approach to 

 the nature of leaves, as in Umbelliferous and Cruciform 

 plants. The difference of duration is still more evident, and 

 more instructive as to our present purpose, in the Leguminous 

 family, between such Cotyledons as rise above the ground, like 

 Lupines, and those which remain buried, like Vetches, the lat- 

 ter decaying as quickly as any supposed Vitellus can do. In 

 Grasses the scale, taken by Gaertner for a Vitellus, is mostly so 

 thin and unsubstantial, as not possibly to contain any material 

 portion of nourishment ; but its expanded figure is very well 

 calculated, like that of the leaves, for functions analogous to 

 vegetable respiration, and its whole aspect conveys the idea of 

 a primary or subterraneous leaf, quickly rendered superfluous 

 by the production of real leaves, which, as well as the radicle, 

 are probably, in the first stage of their evolution, fed by the 

 abundant juices of the Albumen. It appears that the pretended 

 Vitellus is not necessary to all plants furnished with this distinct 

 kind of Albumen. The Palms and Orchidea prove to be desti- 

 tute of it. On the other hand, I can find no instance of a sup- 

 posed Vitellus, and a real Cotyledon or Cotyledons, in the same 

 plant. What Gaertner terms the Cotyledons of Rhizophora, in 

 his tab. 45, appears to me to be the Plumula, and in his descrip- 

 tions of some of the Scitaminece, he evidently takes the latter for 

 a Cotyledon. 



By understanding the Vitellus as a Cotyledon, all ambiguity 

 respecting the component parts of any seed is removed. When 

 the Cotyledons are two or more, the only question is whether 

 the albuminous matter is lodged in their substance, or whether 



vol. ix. 2 e it 



