ON TIIE STRUCTURE OP SEF.DS. 359 



above (he ground, like lupines, and those which remain 

 buried, like vetches, the latter decaying as quickly as any 

 supposed vitellus can do. In grasses the scale, taken by The scale of 

 Gacrtncr for a vitellus, is mostly so thin and unsubstantial, ^^^ 

 as not possibly to contain any material portion of nourish- in its functions, 

 riierit; but its expanded figure is very well calculated, like 

 that of the leaves, for functions analogous to vegetable res- 

 piration, 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 pre- 

 tended vitellus is not necessary to all plants furnished with 

 this distinct kind of albumen. The palms and orchideos 

 prove to be destitute of it. On the other hand, I can find Vitellus nev«*r 

 no instance of a supposed vitellus, and a real cotyledon dr cotyledon, 

 cotyledons, in the same plant. What Gartner terms the 

 cotyledons of rhizopkora, in his tab. 45, appears to me to 

 be the plumula ; and in his descriptions of some of the.?c/- 

 t a mincai, he evidently takes the latter for a cotyledon. 



\ly understanding the vitellus as a cotyledon, all ambigu- Considered as s 

 ity respecting the component parts of any seed is removed, cotyledon. 

 When the cotyledons arc two or more, the only question is, 

 whether the albuminous matter is lodged in their substance, 

 or whether it forms a separate organ. When the embryo is 

 accompanied by a simple undivided organ or seed-lobe, we 

 know it to be a cotyledon by its strict union, or even par- 

 tial incorporation, with the embryo, as in zcwiia*; whereas 

 the pure separate albumen of the true palms has, as in every 

 other instance, no more connection with the embryo, ac- 

 cording- to Gartner's just remark, than is absolutely ne- 

 cessary : and moreover evinces its true nature by the che- 

 mical alteration, and speedy absorption, of its whole sub- 

 stance. The cotyledon, as I considerit, of zamia, as in 



* Mr. R. Brown, who has observed the germination of a large 

 species of zamia in New Holland, assures me that he found no 

 such incorporation of the parts in question as Gaertner has repre- 

 sented in his t. 3, and that the structure and evolution of even part 

 bore an exact resemblance to cycus us described by Mr. Aubert iiu 

 Petit Thouars. 



numerous 



