tott] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 437 
cients less than 0. 50, but half of those derived from this instrument 
are equal to 0.50. 
TABLE IX 
Instrument Plant | C<0.50 C=o0.50 C> 0.50 Total 
PRYSOL er: ° I 3 4 
Integrator ....... POT ee ee I I 2 4 
Martyn... I I 2 4 
os, Physeloo se 4 2 2 re) 4 
Solio” paper....}]| Xanth....... 2 2 fe) 4 
Martyn, 2.2 2 2 ° 4 
Phivselo 2.3 4 fo) 4 
Wynne paper ....}| Xanth....... I 3 ° 4 
Martyn: : 2... 2 2 ° 4 
: Physats 3), ° 4 I 4 
Black therm ..... anh. SF... I 3 ° 4 
Martyn. cs. 2 2 ° 4 
7. From the Hicks integrator and the black bulb thermometer 
evidence is again presented that Physalis is more sensitive to light 
changes than either of the other plants, and it is suggested that 
Martynia may be somewhat less sensitive than Xanthium. 
From the grand averages of table VII we may derive some ap- 
proximate notion of the values to be taken, in general, as correction 
constants in the operation of these instruments. It must be borne 
in mind that the data are inadequate and the conclusions tentative 
in the extreme. 
8. Physalis appears to be about a third more sensitive than the 
two dark cups, which agree well together. Xanthium and Martynia 
appear nearly to equal these cups in sensitiveness. The average 
correction factor for all three plants is 1.075. : 
9. Physalis appears to be about 60 per cent, the other two 
plants only about 25 per cent, more sensitive than the white cup. 
The average correction factor for the white cup is 1.36. 
to. All three plants are somewhat more than half as sensitive 
as the Hicks solar radio-integrator, the average correction for which 
iS 0.59; see 5 above. 
11. The Wynne actinometer and the black thermometer agree 
well in showing a sensitiveness about double that of the plants, 
