36 SYLVA AMERICANA. 



and accordingly we find that plants growing in the shade are 

 etiolated, or devoid of the green hue, until they are placed in the 

 full sunshine. The various shades of color exhibited by different 

 leaves immediately before their fall are effected by similar 

 causes, and consequently are explicable on the same principles. 

 In the same way, too, the variegation of different leaves may be 

 resolved, or at least the agents that produced them may be 

 pointed out. The mode in which these effects are induced, 

 Mr. Ellis does not attempt to detail, being satisfied with the 

 general fact. It would open a field of interesting inquiry, to 

 examine, with care, the gradual changes from green to white, 

 with all the intermediate and collateral varieties of color ; and, it 

 is probable, that in the course of such researches, many valuable 

 facts would develop themselves, and thus tend more clearly to 

 elucidate this branch of vegetable physiology. 



CHAP. II. 



Of the Organs of Reproduction. 



The organs of reproduction, as we have before stated, consist 

 of the flower, fruit and seed. 



It is well understood, that upon the early advance of vegetation, 

 there are to be seen sometimes upon the stem, frequently upon 

 the bulbous roots, and always upon the branches, very small 

 prominences denominated the gem or bud, containing the rudi- 

 ments of future formations ; some expanding into leaves and 

 new branches, some into flowers, and others into flowers and 

 leaves conjointly. 



The flower gem, to which our attention now must be exclu- 

 sively directed, by the progress of vegetation, gradually expands 

 and enlarges until the outline of the flower becomes observable ; 

 when supported by the stalk or peduncle, all the several parts 



