NATURAL HISTORY MISCELLANY. 53 
sulphuric acid, in vacuo. This was found to be from 5.08 to 6.09 
per cent. 3. Amount of transpirable fluid in the stem and leaves, 
7.58 per cent. The remainder, from 56 to 57 per cent., was there- 
fore determined to be fluid in relation to the cell-sap of the plants. 
4. Rapidity of transpiration in sunlight, diffused light, and dark- 
ness. The results given are:—in sunlight, 3.03 per cent. in an 
hour; in diffused daylight, 0.59 per cent.; in darkness, 0.45 per 
cent. 5. Amount of fluid transpired in a saturated, and in a dry 
atmosphere in the sun, and in diffused daylight. In sunshine, the 
experiments gave 25.96 per cent. in an hour, in a saturated atmos- 
phere; 20.52 per cent. in a dry atmosphere ; in the shade the re- 
sults were reversed, nothing whatever in a saturated, 1.69 per 
cent. in a dry atmosphere. These results strikingly confirm the 
earlier experiments of Dehérain, that evaporation from leaves is 
due to light and not to heat, and that it proceeds equally in a per- 
. fectly saturated atmosphere. 6. Quantity of water taken up by 
leaves when immersed in it. The mean of several experiments 
gave 4.37 per cent. in one and one-half hours. 7. Quantity of 
aqueous vapor absorbed by leaves in a secluded atmosphere. 
This was found to be nil, again confirming the statement of M.M. 
Prillieux and Duchartre that plants absorb no moisture whatever 
in the state of vapor through their leaves. 8. Differences in the 
amount of fluid transpired by the upper and under side of leaves 
in the sun and in diffused daylight. From the upper surface in 
sun 1.74 per cent. in an hour, from the under surface 12.33 per 
cent. ; from the upper surface in diffused light 2.82 per cent. in 
forty-eight hours, from the under surface 16.08 per cent.; from 
both sides when coated with collodion, 0.86 per cent. in sun, 2.56 
per cent. in diffused light. 9. Relation of fluid taken up, to that 
transpired, and that retained, by the plant. Increase of weight of 
branch in saturated atmosphere, diffused daylight, in forty-eight 
hours, 7.34 per cent., in ordinary atmosphere, 7.14 per cent., in 
darkness, 3.01 per cent. 10. Rapidity of ascent of fluids. From 
4 7212 inches in ten minutes to 8-7-12 inches in ten minutes. 11. 
Influences of gases on transpiration. Transpiration of fluid in 
. oxygen in one hour in sun, 12.77 per cent., in atmospheric air, 7.5 
per cent., in carbonic acid, 4.01 per cent., in nitrogen, 1.97 per 
cent. The bad weather, and the lateness of the season, terminated 
the experiments before several points of interest could be fully 
determined. — A. W. B. © 
