
1 $05.) ~ On Vegetable Assimilation and Respira tion. «428 
ao 
hed to the south, and left unmoved all: day, the aes bright sun n fell on 
it obliquely, and ( did not peace its full effect.__ 
Experiment VI (I uly 24, 1904), Chetry! laurel; Weight, 1°90. _grammes ; 
Area, 62°6 sq. cm.; Current Rate, 800 c.c.; CO; = 24 per cent. 
. (average). cy anh be 
a ae ne en te cn ee er re eee 
Leaf faced to South ; Boattion unchanged throughout Experiment, 
——— 











, eet Ty. Tempers Tempera- | co, ~~ CO, _ Rea hoes 
Time. Tilumination. ture of ture of ie absorbed |* 
a ae'| See - bath b--deag, --|-SUpplied..| 7 dene —|- Pex hour 
: 5 y teat. | per 50 cm?. 
Beard en Fat fee, neti co 
8.30—9.30 | Dull, cloudy day ... — — Prelim|inary 
9.30—10.30.|,.Alternate . sun-....| [ 18:8 perpen ope rea mpmmnfen ea 
Bn aaa ae i 235° | 0-0408 | 0-0100° ) 00092 
Se cee ee then | {19 2 23-2 | 0:0413 | 0-0103- |. 0-0095 
faint sun 20 2 
11.30 a.m.— | Gleams of sun till 20 °6 : p : Pre 
12.30 p.m. | 12, then dull { 19°5 } ate Use URE ee 
P.M. 
12.30—1.30 | Uniformly dull...... 19 ‘7 21 °4 0 0410 0 0076 0 0071 
| 1.30—2.30 | Brightsunthrough-/ 20-4 26-9 | 0:0360 | 00114 | 0-0108 
Bhs AAS out 
2.30—3.30 | Bright sun, except 20 °7 26 .°3 0 0367 0 :0098 0 0093 
; at 2.50, when a ; 
clouds 
8,30—4.30 | Bright atbeginning 19°9  21°8 | 0-0366 | 0-0062 | 0-0061 
‘and at end; dull. 4 
in middle 
4.30—5.30 | Sun at first, then) 20°00 = 21°5 00372 | 0-0054 | 00054 
. thin cloud | 
5.30—6.30 | Bright sun; sun 19°8 | 20 *4 3 : ; 
and thin cloud | { Oy 19:9 ie Gece ne ee 



The three first readings Her about the same illumination- intensity ; : 
witness the uniform leaf- -temperature and uniform excess of leaf-temperature 
over bath-temperature. As the scattered gleams of sun fall on the leaf with 
decreasing angle of incidence, so the assimilation rises from 0-0092 to 0:0102, 
and gets practically to be maximal for the third reading. In the fourth 
reading a long period of very dull sky brings the assimilation down to 0-0071. 
After that, continuous sun gives the highest assimilation of the day, and the 
highest: excess of leaf-temperature, though a still larger assimilation would be 
expected. From that point the light steadily becomes feebler, and that part 
