EUPHORBIA VI ROSA AND ALOE DICHOTOMA 
47 
December 13. 
Chart I (11 a.m. to 5.30 P.M.). 
Euphorbia A. A large plant of E. virosa situated about 15 yards south of 
the screen (see Photograph 4). Three thermometers (viz. W, T, P) were 
inserted in three branches of this plant. 
Readings were taken every 30 minutes from 5 a.m. to 5.30 p.m. The 
closer series from 9-10 and from 11-12 (Wounding Experiments 1 and 2 
are described later). 
At 5 A.M. the following were the temperatures observed : 
BB, 23° 3 ; Sh, 24°-2 ; T, 23°-5 ; P, 24° 0 ; W, 24°-5 C. 
CHART I. December 13. Euphorbia A (Thermometers W, T, P). 
All except the shade temperature began to rise soon after 5.30. Between 
5.30 and 6 the sun appeared from behind the hill and just touched the tops 
of the branches under observation at 6.30. From this moment they all rose 
more rapidly. T, being illuminated later than the othei two, did not cioss the 
slowly rising curve of the shade temperature until nearly 7 o clock. 
The Black-Bulb (BB) temperature reached its recorded maximum (65'8 C.) 
at 2 o’clock, at which time also P and T are at their highest points, viz. 
51°-5 and 48°‘5 C. respectively. W attains its maximum (47°) one hour later. 
The zigzag character of the BB curve, which is reflected in those of Sh, P W 
and T, is due to passing clouds. The sky was “ overcast ” between 1 and . 
and again between 2 and 2.30, and after 3 the sun was completely hidden. A 
thunderstorm accompanied by wind from the north-east commence at 
