EUPHORBIA VIROSA AND ALOE DICHOTOMA 55 
1 inch above and below the point of insertion of the thermometer. The 
wounding was completed in time to allow a reading to be taken at 1.2, when 
the temperature at the wound had already fallen 1°'5 C. The fall was greater 
than in the preceding experiment, but otherwise very similar. In the 
Wounded branch at ( W) ... total fall = 10 o, 75 C. 
Unwounded „ at (P) ... „ ; = 4°-5 C. 
Wounded „ at (T) ... „ „ = 3° C. 
A striking character ol the temperature curve of the wounded stem very 
clearly shewn in this and in the preceding experiment — may here be noticed. 
The descending half ol the curve is very much steeper than the ascending 
poition, the fall and the recovery not being due to complementary causes. 
And further, the fact that the descending curve is as steep in the first 
3 minutes after wounding as in the succeeding 4 minutes, testifies to the 
importance of the first cause of cooling, assumed to be gas-expansion. 
No. 5. December 15. 
Chart Y. 
Plant. Euphorbia A. 
Thermometers. P, W, T in the same positions as in Experiment 4. 
At 8.2 two furrows of the stem P were wounded in the same manner 
and in the same places as at 10 A.M. on the previous day. The fall of 
temperature began promptly. The total fall was 3 0- 75 C., and the curve at 
the beginning of the descent was much more gradual than in the last two 
experiments. This is no doubt a direct consequence of the extensive 
wounding at the same place 22 hours earlier. The exhaustion of the latex 
caused a much reduced exudation in this experiment which means not only a 
reduced evaporation at the surface but also a smaller expansion of internal 
gases — perhaps even no expansion at all. If this is correct, then on the 
hypothesis stated above, the thermometers W and T, in a branch which in 
this experiment was not wounded, should shew little or no response. This is 
exactly what occurred. If a fall occurred in either of these thermometers it 
was less than 0°’25 C. 
No. 6 and 7. December 16. 
Plant. Euphorbia B. 
Thermometers. Iv, in a branch on the eastern side of the plant ; 
W, 14 cm. below the apex of a branch on the western 
side of the plant. 
At 9.35 A.M. the upper 7 cm. of the stem W were removed by a clean 
transverse cut, leaving the thermometer 7 cm. below the new apex. Two 
minutes later W shewed a fall of 0 C '75C. It then became stationary for 
