Page:Journal of botany, British and foreign, Volume 9 (1871).djvu/31

 THE TRANSPIRATION OF WATERY FLUID BY LEAVES. 21

(11.) Amount of fluid transpired in a saturated atmosphere in sun, one

hour, 2 5 '9 6 per cent. (12.) Ditto, dry atmosphere, 20"52 per cent.

In the shade the results were very different.

(13.) Amount of fluid transpired in a saturated atmosphere in the shade, one hour, '0 per cent.

(14.) Ditto, dry atmosphere, 1'69 per cent.

VI. Quantity of water taken up by leaves when immersed in it. The mean of several experiments gave, when the leaves were immersed for an hour and a half, (15) 4-37 -per cent. — VII. Quantity of watery vapour absorbed by leaves in a saturated atmosphere. By placing branches in a saturated atmosphere for eighteen hours, they were found not to have lost weight in the least, or (16) '0 per cent. — VIII. Differences in the amount of fluid transpired by the upper and under sides of leaves in the sun and in diffused daylight. One or both surfaces of the leaves were covered with plastic collodion, which formed a strong film on the leaf, and effec- tually prevented the transpiration of fluids.

(17.) Amount of fluid transpired by upper surface of leaf in sun, one

hour, 1"34 per cent. (18.) Ditto, under surface, 12'33 per cent. (19.) Ditto, both sides coated with collodion, 0-96 percent. (20.) Ditto, by upper surface of leaf forty-eight hours in diffused light,

2-82 per cent. (21.) Ditto, by under surface, 16'08 per cent. (22.) Ditto, by both sides coated with collodion, 2*5 6 per cent.

IX. lielation of fluid taken up to that transpired and that retained by the j)lant. In these and the other experiments a branch of Laurel was taken, and fixed in a short test-tube containing a little water. The branch was passed through a cork, and the whole carefully closed with melted paraffin. By weighing the water in the tube, the branch and the whole apparatus, both before and after the experiment, the loss in the tube, the gain of the branch, and the amount transpired, could be determined.

(23.) Total amount of

fluid taken up. 1-088 granune. Amount transpired. 0*040 Deduct. . .1-038 Gain of weight of branch 0398

��Unaccounted for 0-05 I'OoS

(24.) Increase of weight of lirancli in saturated atmosphere, diffused

daylight, forty-eight hours, 7 34 ])cr cent. (25.) Ditto, ordinary atmosphere, 7"14 per cent. (26.) Ditto, ditto, darkness, 3-01 per cent.

X. Rapidity of ascent of fluid in plants. The experiments made under 111. aftbrded data for measuring the rapidity of ascent of fluid in plants. Tlie branch was placed in a test-tube, with a small (juantity of solution of lithium citrate. The branch was then placed in the sun for a certain time, and when removed was cut in pieces, each piece consisting of an in- ternode, petiole and leaf. These were measured, nunilicred, and care- fully dried in the water oven. When dry, each portion was tested by means of the spectroscope for lithium.

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