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. 



