ON A. LAURENT DE JUSSIEU. 53 



respect of the seed. The most interesting question, perhaps, 

 in the whole range of vegetable physiology, is to determine 

 the peculiar function of each portion of the flower. 



A flower, as every body knows, consists of many parts. In 

 the centre is the Pistil or female organ ; round it are placed 

 the Stamens or male organs; the Corolla or brilliant portion, 

 which constitutes the coloured part of the flower, (the flower 

 itself, according to Tournefort,) surrounds the stamens; while 

 the calyx, a prolongation of the outer laN'er of bark or epi- 

 dermis, encloses the whole. 



More than a century and a half after Gessner, Tournefort 

 was still in ignorance of the use of stamens, and even denied 

 it, when Vaillant demonstrated the Hict. The theory of the 

 latter writer on the sexes of plants, was brought into notice 

 by the ingenious system of Linnaeus, subsequently confirmed 

 by Linnseus', Gleditsch's, and Koelreuter's searching expe- 

 riments, and thus was the physiological difficulty explained. 



The problem relative to the method, was never solved till 

 Jussieu did so. He perceived that the corolla and calyx 

 were deficient in a great number of plants, while the pistil 

 and stamens, (those reproductive parts of the embryo or new 

 plant,) always exist; taken separately, each of these organs 

 only conveys incomplete characters, while the complete and 

 natural characters are afforded by these two organs taken 

 together, and considered as to their respective insertion. 

 Thus the Insertion of the Stamens forms the primary charac- 

 ter in the flower. 



The primary distinctive character of the seed is derived 

 from tlie lobes of the embryo, or rudiment of the future plant, 

 of which they are the first leaves, the organ which furnishes 

 it with its first aliment. We must therefore be easily con- 

 vinced how much the simple and remarkable differences that 

 are perceptible in these primary organs must influence the 

 general development of the plant and its entire organiza- 

 tion. All the other parts of the seed, which are extraneous 

 to the future plant, and constitute, properly speaking, the 



