porebueh
Tổng số bài gửi : 5
Join date : 11/07/2011
 | Tiêu đề: It is to the action of leaves  Mon Jul 11, 2011 3:33 pm | |
| It is to the action of leavesIt is to the action of leaves,—to the decomposition of their carbonic acid, and of their water; to the separation of the aqueous particles of the sap from the solid parts that were dissolved in it; to the deposition thus effected of various earthy and other substances, either introduced into plants, as silex and metallic salts, or formed there, as the vegetable alkaloids; to the extrication of nitrogen; and, probably, to other causes as yet unknown,—that the formation MBT Shoes UK of the peculiar secretions of plants, of whatever kind, is owing. And this is brought about principally, if not exclusively, by the agency of light. Their green colour becomes intense, in proportion to their exposure to light within certain limits, and feeble, in proportion to their removal from it; till, MBT in total and continued darkness, they are entirely destitute of green secretion, and become blanched or etiolated. The same result attends all their other secretions; timber, gum, sugar, acids, starch, oil, resins, odours, flavours, and all the numberless narcotic, acrid, aromatic, pungent, astringent, and other principles derived from the vegetable kingdom, are equally influenced, as to quantity and quality, by the amount of light to which the plants producing them have been exposed. 7u It is evident that tho possibility of tho downward distribution described in the previous paragraph rests upon the certainty that elaborated sap descend-, and is dispersed through the system. That this occur- is so < our to appear-* it as formation it- or wood, of existcnec the questioning tantamount is deny To question. in call ventured not had naturalists modern some if proof further hy maintain needless been have would that rtain,>MBT Shoes yes when the bark is >tripped from a youau ^rowii.u" shoot ; a- in a Lilac for example. | |
|
shop89
Tổng số bài gửi : 10
Join date : 16/07/2011
| | Tiêu đề: Re: It is to the action of leaves Sat Jul 16, 2011 4:32 pm | |
| | |
|
