H. BOTANY AND HORTICULTURE. 295 







remain green, -the subsequent development of more sombre 

 tints being evidence of more complete death. This change 

 may occur without the agency of frost, but is generally 

 brought about prematurely when subjected to the influence 

 of the latter. 1 A, March 31,150. 



THE MOVEMENT OF CHLOROPHYL GRAINS. 



Dr. B. Frank contributes to the Botanisclie Zeitung some 

 observations on this subject. He confirms the statement of 

 Famintzin and Borodon as to the motion observed in the 

 grains of chlorophyl in the leaves of plants under the action 

 of light, and identifies it with the movements of the proto- 

 plasm previously observed by Sachs. The protoplasm alone, 

 he believes, possesses this power of motion, and carries the 

 grains of chlorophyl along with it. It takes place not only 

 in direct sunshine, but also under the diffused light of the sky. 

 Colored rays, as blue and red, also produce decided though 

 less energetic action. 



TRANSPIRATION OF WATER BY LEAVES. 



In a paper by Dr. MacNab on the transpiration of water 

 by leaves, he states, as the general conclusions reached by 

 his investigations, that the mean of several experiments gave 

 about sixty-three per cent, as the quantity of water con- 

 tained in the leaves, and that the quantity of water remova- 

 ble by chloride of calcium or sulphuric acid was not equal to 

 that transpired under the stimulus of the sun. About five 

 per cent, of the water was determined to be fluid, in relation 

 to the cell sap of the plant. About three per cent, per hour 

 was given out under the sunlight, a little over half of one per 

 cent, in diffused light, and less than half of one per cent, in 

 darkness. About twenty-six per cent, per hour was trans- 

 pired in a saturated atmosphere in the sunshine, and twenty 

 and a half per cent, in a dry atmosphere, while in the shade 

 none was transpired in a saturated atmosphere, and less than 

 two per cent, in a dry atmosphere. Leaves immersed in 

 water take up a little over four per cent, in an hour and a 

 half, and it was established that plants absorb no moisture 

 whatever in a state of vapor through their leaves. In light 

 of any kind the under side of leaves was found to transpire 

 much more water than the upper. The experiments of Dr. 



