Page:Philosophical Transactions - Volume 095.djvu/112

98 g8 Mr. ICNiGHt concerning the State in which

as they do when growing m tJie *best mould. But the water m this case, provided that it be perfectly pure, prdb&bly af?brds Ktde or no food to the plant, and acts only by ^tfssolving the

matter prepared and deposited in the preceding year; and hence

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the root becomes exhausted and -spoiled: and HASStNttiATzTound that the leaves and flowers and roots of strch ^plants affi!*dfed no

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more carbon than he had proved to exist inlnilbous jrootis of <he same weight, whose leaves and flowers Tiad never expanded.

As the leaves and flowers of the hyadnth, in the preceding case, derived their matter from the bulb, it appears extremely probable that the blossoms of trees receive fteir nutriment firom the alburnum, particularly as the blossoms of many spedes precede their leaves : and, as the roots of plants become weak- ened and apparently exhausted, when they have aflbtded mttri- ment to a crop of seed, we may suspect that a tree, which has borne much fruit in one season, becomes in a similar way exhausted, and incapa^ble of affording proper nutriment to a crop in the succeeding year. And I am much inclined to befieve that were the wood of a tree in this state accurately weighed, it would be found specifically lighter than that of a similar tree, which had not afForded nutriment to fnut or blossoms, in the preceding year, or years.

If it be admitted that the substance which enters into the composition of the first leaves in the spring is derived from matter which has imdei^one some previous preparation within the plant, ( and I am at a loss to conceive on what grounds this can be denied, in bulbous and tuberous rooted plants at least, ) it must also be admitted that the leaves which are generated in the summer derive their substance from a similar source ; and this cannot be conceded without a direct adnnssion of the