232 Inquiry into the Structure of Sezds. 



or cotyledons, together with a separate albumen, in seeds, 

 seems to me so unusual, as not to occasion much difficulty ? 

 and 1 would define a coiyledon to be a vital organ, capable, 

 as such, or" being stimulated by oxygen, heat, or both, for 

 the propulsion of its contents ; while such an albumen is 

 merely a repository of nutritious vegetable matter, subject 

 to the laws of chemistry alone, and only passivejy resigning 

 those contents to the absorbing powers of the embryo, to 

 which it is attached. 



I must now, under the impression of what has just been 

 advanced, return to the arrangement of plants by their co-? 

 tyledons. 



Plants in general are dicotyledonous, having a pair of 

 these organs, which commonly rise out of the ground j but 

 if they do not, it appears, from the ■consideration of the 

 leguminous tribe, that such a difference could scarcely serve, 

 for a generic distinction, much less for that of a class or 

 order. It also appears that, if the number of cotyledons 

 exceeds two, as in pirius and a few other instances, the dif- 

 ference is of little or no use for systematical purposes, and 

 of no physiological importance whatever. The cotyledons 

 of pinus all present their backs to receive the oxygen. 



Some plants appear to be really furnished with one aim* 

 pie cotyledon, as zamia, and according to Gaertner's figures 

 and descriptions, the true scitaminece, as amomum (his zin- 

 giber), alpinist, &c; while carina seems to have no cotyle- 

 don, but only an albumen. Can this be true ? and if so, 

 what is the value of such a distinction in a natural classifi- 

 cation ? The liliacece, palmce, and now the orchidete, are 

 acknowledged tp be acotyledonous, having only an albumen; 

 while the grasses, so nearly allied to them, have one cotyle- 

 don, for I presume their scale must be admitted as such. 

 Gartner's phrase of embryo monocoiyledoneus applied to. 

 these last mentioned families may occasion a mistake, whicfy 

 would be avoided by the term embryo simplex, or indivisus,. 

 expressing his idea of the simple figure appropriate to this, 

 part in such plants, but which does not prevent its upper 

 extremity being strictly analogous to the plumula of the di~ 

 cotyledones. It seems to me therefore that this learned writer 



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