3 88 
McLean . — Field Studies of the Carbon 
This exceptional behaviour of the detached pinnae indicates that possibly 
the midday decline in carbon dioxide absorption of the attached coco-nut 
leaves tested may have been due to incipient drying or some other unfavour- 
able condition imposed upon the leaf by the condition of the rest of the 
plant. 
Series 8 and 9. 
The two series of tests Nos. 8 and 9 of abaca leaves (Musa textilis ) 
were made on a detached leaf on May 18 and on a leaf of a potted plant on 
May 31. In these tests the tubes used in the other tests to enclose the 
leaves were replaced by flat chambers 2 cm. deep and 90 cm. long with 
glass walls at top and bottom, the sides being supplied by movable wooden 
strips, fitted snugly against top and bottom plates by rubber strips. By 
this means the size of the chamber was adjusted to conform to the width of 
the leaves. Apart from this modification, necessitated by the broad abaca 
leaves, which resemble banana leaves, these tests were similar to those of 
sugar-cane and coco-nut. The results are shown below in Tables VIII and 
IX and Diagrams 8 and 9. 
Table VIII. 
Carbon dioxide absorption by a detached abaca leaf of 472-63 sq. cm. 
area on May 18, 1918. 
Difference in 
concentration of 
C 0 2 absorbed 
Duration of 
Ba , 0 H) 2 from test 
CO 2 absorbed 
per sq. m. per Remarks 
Test. 
and control in c c. 
of 0-040* normal 
per sq. m. 
hour. 
HCl. 
mg. 
mg. 
5 3 °“ 7 - 3 ° a - m - 
0*45 
102 
51 Sunrise at 5.48. 
7.30- 9.30 „ 
0*20 
4 5 
23 Bright until 2.30 p.m. 
9.30-1 1.30 ,, 
C * T 5 
34 
17 
11.30 a.m.- 7.30 p m. 
0-20 
45 
2 3 
1 30 - 3 - 3 ° P<m. 
0-30 
68 
34 Rain 2.30 to 4 p.m. 
3 - 3 0 - 5 - 3 o „ 
o*i 5 
34 
17 Cloudy from 4 p.m. to 
5.30-6.30 „ 
0 0 
328 mg. 
Table IX. 
0 the end of exp. 
Carbon dioxide absorption by 
a leaf of 309*35 sq. cm. area of a potted 
abaca plant on May 3 
Difference in 
concentration of 
1, 1918. 
C0 2 absorbed 
Duration of 
Ba(OH)vfrom test 
C 0 2 absorbed 
per sq. fn. per Remarks. 
lest. 
and control in c.c. 
of 0-0405 normal 
per sq. m. 
hour. a eniartcs. 
7 / Cl. 
mg. 
mg. 
5.3c- 6.30 a.m. 
0-30 
!03 
103 Sunrise at 5.45 a.m. 
6.30- 8.30 „ 
°‘35 
121 
60 Sunshine on leaf at 6.10 
8.30-10.30 „ 
o' 2 5 
86 
43 a.m. 
to. 30 a.m.-i 2.30 p.m. 
O ' 1 5 
5 2 
26 Bright sunlight through- 
j 2.30-2.30 p.m. 
0-15 
5 2 
26 out the day. 
2 30-4.30 „ 
0-10 
34 
17 
4.30-6.30 „ 
O-IO 
34 
482 mg. 
l 7 
