418 
Journal of Agricultural Research 
Vol. XXXI, No. 5 
Fig. 1—The relation of the daily leaf growth of four date palms at the United States Date Garden 
at Indio, Calif., throughout the year 1917 to the daily mean temperature. The temperature 
is plotted in 6*and 7-day periods and the mean growth in millimeters for corresponding periods 
on the basis of zero of growth at a mean of 40° and a gain of 1 millimeter in the daily growth 
rate for each rise of 2° in the daily mean temperature 
