vegetable physiology. 41 



are commonly two in number, but sometimes four, and in others 

 only one. When the seed has sufficiently established its root, 

 these generally rise out of the ground, and become a kind of 

 leaves. Such is the true idea of the organs in question, but the 

 same name is commonly given to the body of the seed in the 

 grass and corn tribe, the palms, and several other plants, thence 

 denominated monocotyledons, because the supposed cotyledon is 

 single. It neither rises out of ground, nor performs the proper 

 functions of a cotyledon, for, what these plants produce is, from 

 the first, a real leaf; or, if the plant has no leaves, the rudiment 

 of a stem. 



The albumen, or white, is a farinaceous, fleshy, or horny 

 substance, which constitutes the chief bulk of some seeds, as 

 grasses, corn, palms, lilies, never rising out of the ground nor 

 forming the office of leaves, being destined solely to nourish the 

 germinating embryo, till its roots can perform their office. In 

 the datepalm, this part is nearly as hard as stone ; in the 

 JWirabilis jalap a or four o'clock, it is like wheat flour. It is 

 wanting in several tribes of plant, as those with compound, or 

 cruciform flowers, and the cucumber and gourd kind, according 

 to Gsertner. Some few leguminous plants have it, and a great 

 number of others, which, like them, have cotyledons, besides. 

 We are not however to suppose that so important an organ is 

 altogether wanting, even in the above mentioned plants. The 

 farinaceous matter, destined to nourish their embryos, is un- 

 questionably lodged in their cotyledons, whose sweet taste as 

 they begin to germinate, often evinces its presence, and that it 

 has undergone the same chemical change as in barley. The 

 albumen of the nutmeg is remarkable for its. eroded variegated 

 appearance, and aromatic quality ; the cotyledons of this seed 

 are very small. 



The vitellus, or yolk, first named and fully illustrated by 

 Gaertner, is less general than any of the parts already mentioned. 

 He describes it as very firmly and inseparably connected with 

 the embryo, yet never rising out of the integuments of the seed 

 in germination, but absorbed, like the albumen, for the nourish- 

 ment of the embryo. If the albumen be present, the vitellus is 

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