EVERGREEN TREES IN WINTER. 343 



piraiion between two serîes of observations was great, and can be 

 indicated at about 1 : 20. 



Recently, Kosaroff in his dissertation, quoted above, has 

 experimentally shown that rooted plants as well as cut-branches 

 can absorb water even under 0°C.; and also that in the stem 

 of trees water can pass through when a portion of the stem is 

 cooled below 0°C. My experiment has been carried on with the 

 view of ascertaining the mode of absorption of water by plants 

 when they are exposed to extreme cold. Such conditions com- 

 monly occur in plants on cold winter morning when the leaves 

 are sometimes frozen stiff. As is well known, the absorption of 

 water by cut-branches, in ordinary air temperature, is greatest 

 at first in consequence of the negative pressure of gas, and gradu- 

 ally diminishes as the pressure comes to an equilibrium. How- 

 ever, when the branches were cut off on a cold winter morning 

 and were brought into the room, a quite different phenomenon 

 was found to occur ; the power of absorption was at first very 

 weak but after a short time, it suddenly increased and then 

 sank gradually until it became constant in each succeeding 

 interval. As it appeared to me that this fact might have a 

 close connection with the process of transpiration on a cold 

 morning, I endeavoured to examine it more closely. 



In the middle of last winter I cut off some shoots and im- 

 mediately measured the amount of water absorbed by them in a 

 room in which a nearly constant temperature above 0°C. was 

 maintained. In Daphniphyllum macropodum and Aucuba japonica, 

 the alteration of the absorbing power was remarkable. In the 

 former plant (see Table X) 8 mm. of water column was absorbed 

 during the first hour, but after one hour 245 mm. was absorbed 



