360 . OS THE STRUCTURE OP SEEDS. 



numerous parallel instances, shrivels and shrinks indeed con- 

 siderably, from the absorption of its albuminous contents 

 by the vegetating embryo, but does not disappear, leaving 

 only a skin behind, like the albumen of grasses or corn, bo- 

 cause that part of its substance, which is destined to perform 

 the office, essential to a cotyledon, concerning air, merely 

 decays when its end is answered. 

 Difference in It may further be observed upon this subject, that the 

 the albumen, albuminous matter of seeds with two or more cotyledons is 

 commonly of an oily nature, while those with one cotyledon, 

 or none at all, have a more farinaceous, or even stony, al- 

 bumen. Still the latter changes to a milky or oily tluid, 

 previous to its absorption. When the vital principle of a 

 seed is extinct, its albuminous oil becomes rancid, and, 

 even in seeds that retain life, is liable to suffer some dete- 

 rioration by keeping. Hence, as Darwin observes, gar- 

 deners preserve melon and cucumber seeds, perhaps for 

 years, that the plants they produce may be less luxuriant, 

 in consequence of being starved at their first germination ; 

 for any injury to the cotyledons, even after they begin to 

 rise above ground, is found to cramp the subsequent growth 

 of the plant. 

 Oil of the eo- The oil of the cotyledons has been usually supposed a 

 tyledons. protection to their internal parts, I presume against wet ; 



but this purpose it by no means does or can answer, for all 

 seeds readily absorb moisture whenever they meet with it, 

 and, if likewise exposed to the action of oxigen, they ve- 

 getate, in whatever situation they may otherwise happen to 

 be. I suspect moreover that the oily and mucilaginous flu- 

 ids of seeds in general, before they perform their office in 

 germination, all previously become milky, and often sac- 

 Would oxipen charine, from the actions of water and oxigen. It might 



preserve seeds fo e wor th while to inquire, whether exposure of such seeds 



prone to turn . . - 



nwcid ? as are most prone to turn rancid, to a quantity of oxigen, 



would fend to preserve them. It is, I believe, found, that 



the admission of some atmospheric air is necessary to the 



preservation of many seeds. The primary cause of decay 



therefore in seeds spoiled by keeping may originate, not, as 



I have supposed, in the extinction of their vital principle, 



but in the corruption of their albuminous oils ; and this is 



strengthened 



