Inquiry into the Structure of Seeds. 223 



fhious, or no longer necessary. But all cotyledons do not 

 ascend out of the earth, nor assume any of those functions 

 ■of leaves in which lifht is concerned. In the horse chesnut, 

 ■the cyamus nelumbo, the tropceolum majus, and some other 

 plants, they always remain bur.ed, no doubt acted upon by 

 the air or gas alone. Even in plants of the same natural 

 order, papilionazece, some, as luplnus, raise their cotyledons 

 into the air 3nd light, in the form of very conspicuous green 

 .seed-leaves ; while others, as lathyrus, retain them under 

 ground, concealed in the black skin of the seed, quite out 

 of the reach of every ray of the latter. In these we know a 

 farinaceous albumen is lodged, whether they rise into the, 

 light or "not; and the closest analogy leads us to conclude 

 that their functions are otherwise similar, which can only 

 be with respect to air. Even cotyledons however are not 

 indispensably requisite to a seed, though the albumen ap- 

 pears to be, in some form or other, necessary to all seeds. 

 Not to mention the tribes of vegetables allowed or guessed 

 • to be without cotyledons, and thence, for systematical con- 

 venience, denominated acotyledonous ; all, who have suf- 

 ficiently considered the matter, know that in those called 

 monocotyledonous, what is vulgarly taken for the cotyledon 

 is really an albumen, a part fundamentally distinct in func- 

 tions from what is proper to a cotyledon. Thus even so 

 conspicuous a family of plants as the orchidece, which the 

 faithful Jussieu confesses were only presumed from analogy 

 to be monocotyledonous, or, as he guardedly expresses it, to 

 have " a single-lobed corculum, : ' have been shown by Mr. 

 Salisbury, in the 8th volume of cur Transactions, the only 

 person I believe who has well, examined their germination, 

 to have in fact an albumen, but no cotyledon atiill. Nor 

 does such ambiguity or uncertainty belong to. this family 

 alone. Many plants are. presumed to be monocotvltdonous, 

 chiefly because they grow in the wat^r ; and it is much to 

 be regretted that this fundamental principle of all natural 

 systems should in many cases be so ill-established, and very 

 often so extremely difficult toxletect or to determine; which 

 happens in general where its help is most wanted, -as I shall 

 V©L 32. No. 127. Dec. 180S. P presently 



