rftt THE STRUCTURE OF SEEDS. 



h'rips the skins of some fruits. It is, moreover, evident, 

 rttat all the indispensable functions of the cotyledons are 

 best performed under ground, and that when they rise into 

 the air and light, it is not till after their primary destination 

 is fulfilled, and then because, being fundamentally of the 

 nature of leaves, they are also capable, in most instances, 

 of assuming their functions with respect to light, ft is 

 highly worthy of notice, that, in consequence of the original 

 position of the cotyledons in all seeds, the oxigen gas must 

 always be imbibed by their under side, that very same part 

 which in leaves gives out this kind of gas during the day, 

 and probably absorbs it during the night. It would have 

 evinced a strange contrariety in the constitutions of two or- 

 gans otherwise so analogous, I mean the leaves and cotyle- 

 dons, if the upper surface of the latter, while in the unex- 

 panded seed, had been presented to receive the oxigen gas. 

 Stalk of the Where there is a separate albumen, without any pcrccp- 



embryo may tible cotyledons, it is probable that the stalk of the embryo 



perform the , 



function of a may* answer the necessary purpose; just as the stems of 



cotyledon, leafless plants must be presumed to perform the usual chc- 

 ter is wanting. mical functions of leaves, though we cannot ascertain in 

 what direction the different airs are imbibed or discharged, 

 there being no decided upper or under surface in such stems, 

 any more than in crisiform leaves. Such, however, are 

 rare exceptions, which if not, as yet, found to throw any 

 new light on the subject, certainly do not overturn any im- 

 portant part of the above hypothesis. That some part, im- 

 mediately connected with the embryo, must be stimulated in 

 order to excite the germination of a seed, this phamomcrion 

 being dependent on the vital principle, is evident. I con- 

 ceive that, when present, the cotyledon or cotyledons are 

 themselves simulated by the oxigen gas, or rather by the 

 heat which chemists inform us is produced by the absorption 

 of this gas, so as ib set their fluids in motion, and thus to 

 ♦ pTopel the young root and rising plumula. Rut when the 

 cotyledons are wanting, the embryo may very well be con- 

 ceived capable of sufficient action, to imbibe for itself the 

 juices of a distinct albumen, already become milky and sac- 

 charine by the reception of oxigen and moisture; by which 

 merely chemical process, as in barley, so considerable a de- 

 gree 



