131 
of plants, yet several promising avenues for investigation are 
opened up. 
It is to be recalled that numerous and extensive data of soil 
temperatures at various depths have been obtained by many ob- 
servers, chiefly by means of mercurial thermometers, or by elec- 
trical apparatus.* It is believed however that the above appara- 
tus will offer many advantages in the way of securing continuous 
records, as well as data as to the rate and manner of variation 
that will be of great value in the investigations under way, and 
also in other questions connected with the growth and activity 
of plants. 
D. T. MacDoucat. 
EFFECT OF LIGHTNING ON TREES. 
Five trees in the Garden have been “struck” by lightning in 
three years. One of these, a fine example of swamp oak 
(Quercus palustris) which stood near the railroad station in the 
western part of the grounds, conducted a discharge in July, 
1901, which traversed the trunk and one of the two main “ forks” 
into which it divides. The spark or flash appeared to pass through 
the uppermost twigs of this main branch, variously splitting and 
rupturing the tissues, and tore the bark, growing layer, and sap 
wood, in places from the surface of the main branch and trunk 
in a band 8 to 12 inches in width. The lowermost branches of 
the fork traversed survived and sent out a few leaves in 1902, 
but the remainder, as well as the lowermost branches of the other 
fork, were unmistakably killed immediately by the shock. The 
* General Considerations on Soil Temperatures. Rep. N. Car. Exp. Sta. Pp. 92- 
: 86 
1886. 
Whitney and Briggs. An — ical Method of Determining the Temperature of 
Soils. ey No. 7, U. S. Dept. of Agriculture, Division of Soils, 18 
Briggs, L. J. Electrical ae for oe ae spre eniiets ure, 
and Soluble Salt Contents of Soils. Bull. 15, U.S. t. of Agriculture, ey 
sion of Soils 1899. 
also Reports N. Y. Exp. Station for observations extending over a number of 
years, 
ome important phases of the subject are set forth by D. A. Seeley in an article 
The aa of the Soil and the Surface of the Ground, Monthly Weather 
Review, 29: No. 5, p. Igor. 
