29 MARCH 1924, Page 15

THE INTERNAL TEMPERATURE OF TREES. [To the Editor of the

SPECTATOR.]

SIR,—For some time now I have been trying, in vain, to obtain any concrete knowledge as to the minimum internal temperature of trees and shrubs. This, in view of the heavy cold they experience (and live through) not killing them or bursting the bark, must be of some easily measurable magni- tude. Moreover, during the coldest winters one can observe the buds of such trees as the horse chestnut or the lilac visibly swelling. Perhaps you or some of your readers would be so very kind as to furnish me with any information they possess.

Also, although not wholly devoid of scientific acquirements, I fail to realize what actual known power exists that raises the abundant sap to the twigs and leaves of high trees, and maintains it in position. All such actions are usually ex- plained by capillary attraction, but this is a beautifully vague expression that truly explains nothing, and can only be com- pared to the equally vague expression of electrical attraction so far, at any rate, not satisfactorily explained to me.

In both the above cases there is surely an immense field for research, but it is, of course, quite possible that there may be a mass of information available.—I am, Sir, &c.,

Betchzvorth. PHILIP DUMAS, Rear-Admiral.