2) The Philippine Journal of Science 1917 
lation are too slight to be measured, although, theoretically, they 
may occur. Reinke ** and Pantanelli** both found a light inten- 
sity, about equal to direct insolation, beyond which further 
increases in illumination augmented assimilation very little or 
not at all., There is, however, no reason to believe that at such 
intensities the order of the temperature coefficients would be 
changed. The low coefficient obtained by van Amstel with light 
of such high intensity that further increase in illumination 
caused no measurable increase in assimilation is in harmony 
with this view. A photochemical reaction, with such intensi- 
ties of light, would still be photochemical and should show pho- 
tochemical coefficients. It seems reasonable to assume, there- 
fore, that the temperature coefficients for assimilation in cherry 
laurel, for temperatures between 3° and 33° (and perhaps even 
higher temperatures), is either 1.00 or a slightly larger figure, 
rather than 2 or more. 
- Tables VITI and IX in Matthaei’s publication deal with pre- 
liminary experiments in which the temperature of the leaf was 
not determined. These are not used by Matthaei in building 
her curve and are of no interest here. 
Table X is headed, “An experiment with a Keith high pressure 
burner showing the unavoidable rise in the assimilation maxi- 
mum that results, with each augmentation of the light intensity, 
from the decided increase of internal leaf temperature that the 
radiation produces, in spite of the bath temperature being kept 
constant throughout.” The results of this table are summarized 
in Table 10 of the present paper. 
TABLE 10.—Summary of Sra’ X (Matthaei). 
vei 
Light milation 
Experiment No. Date. Temper-| jiten.| Pet 
ee ate. ature. ao per 50 sq. 
ems., in 
grams. 
1903. ne, 8 
18.5 | 18.5 0.0100 
Mar. 12-15 ou. ----2..-.----.--... 15 9.25} 0.00685 
13 4,75 0. 00555 
13 4.15 0. 0059 
LV pipe a pi De tera ueb set lw s0e pen PRR ee Bar Sh Mar. TB re ee See ee | 11 2.87 0.0039 
il «4147 0.0024 
Mae Se { ll 1.47 | 0.00305 
li 0.73 0.00185 
* Reinke, J., Untersuchungen iiber die Einwirkung des Lichtes und die 
Sauerstoffausscheidung der Pflanzen, Bot. Zeit. 41 (1883) 697. 
rr E., Jahrb. Wiss. Bot. 39 (1904) 167-228. 
