1914] HASSELBRING—EFFECT OF SHADING 277 
average leaf area per plant of those grown in the shade was 8000 
sq. cm. greater than that of the plants grown in full light. Yet, as 
we have seen, in spite of this great difference in leaf area, the shade 
plants used about 1o liters of water less per plant than the sun 
plants. The hourly transpiration per unit of leaf surface was 
nearly 84 per cent greater in the plants in the open. The actual 
hourly transpiration was probably double that given in the tables, 
since the calculation was based on a 24-hour day, while the plants 
did not transpire perceptibly during at least 12 hours of that time. 
Such a change would not, however, alter the relative value of the 
figures which chiefly concern us here. 
A comparison of the rates of transpiration from the leaves dur- 
ing the last five days with the rates of evaporation from the porous 
cups during the same period of time shows a fairly close relative 
agreement between transpiration and physical evaporation. The 
ratio of transpiration in the shade to that in the open is 1:1.8; 
while the ratio of evaporation from the atmometers in the two 
Stations is 1:2. 1. 
The data relating to the fresh weight of the plants are given in 
table VIIT 
TABLE VIII 
FRESH WEIGHT OF PLANTS 
oe OPEN 
No. of plant Leaves Stems Roots Total 
BR eee ge 
i e 
eter oe 409 364 246 101g 
; eh eee 365 335 199 89 
pes... 433 407 233 ae 
Chee 371 388 182 941 
eo: 412 308 197 ord 
Pes w ey lo 416 3890 215 1020 
Average 4or 380 212 993 
SHADE 
UU ene 
ra Whe egg eS 451 508 257 1216 
ee. 44 494 i ssi 
os 467 479 193 bar 
a eerie 461 466 186 I1t3 
eo -: 488 483 203 E574 
Salty AT ie ce ee 502 503 180 I 185 
Average Ee, 469 489 205 1162 
Ge ie mane 
