420 Dr. F. F. Blackman and Miss G. L. C. Matthaei. [Apr. 11, 
Experiment III (July 14, 1904).—Cherry-laurel; Weight, 1°75 grammes; 
Area, 55°1 sq. cm.; Current Rate, 800 ec; CO. = 2°5 per cent. 
(average). 
Leaf-chamber adjusted Normal to Sun throughout the Day. 

—__—_—__—__, 





Real 
Tempera- CO, pce aee 
Time. Illumination. ture of os absorbed assimilation 
Gly supplied. by leaf, per hour 
per 50 cm?. 
A.M. in 
9.35—10.35 Brightisunshine* 2) ..--. =. 18 a Preliminary 
IOs =k soeimllaehe clouds Mn.eesar eee { oe } 0-0392 | 0-0089 | 0-0090 
Pen \ | Grey clouds; then less dull { a 6 0 0387 0 0079 0 ‘0081 
P.M. 18 °5 
12.35—1.385 | Sun; cloudy ..............00. 1 pate i 0:0415 | 0-0092 0 -0093 
18 °2 
1.35—2.35 | Mostly sun .......ecceeeee. { age 
2.35—3.385 | Dark clouds .................. 18 6 0 :0396 0 0064 O 0067 
3.35—4.35 | Overcast till 4.5; sun...... { ae \ 0-0398 | 00071 | 0-0077 
4.385—5.35 Sun behind chimney ; last 23 °5 P ‘ " 
| half hour, sun { 26 -6 } 0 :0405 0 °0108 0°0111 
5.35—6.35 | Sun through thin cloud os Sake i 00405 | 0-0100 | 0-0108 
| 4 
6.35—7.35 Sun below roof ; thin cloud { Sane ' 0-0390 | 0-0033 | 00043 
7.385—8.35 | umsetcOel li ctr eratneaee 20 °O 0 °0401 0 -0002 0 -O010 
| : : minus 
8.385—9.35 | DGSKa cect sn eae 18 °4 0 :0376 0 -0009 



Experiment IV is the first with a leaf of Helianthus tuberosus. This leaf 
had been set up for an experiment on the previous day with a thermo- 
junction in it, but owing to trouble with the galvanometer-leads the 
experiment was abandoned, and re-started the next day with the same leaf 
still in the chamber. 
On this afternoon took place the most violent rain and thunder storm of 
the year, and assimilation estimations were taken through it. The first 
reading shows how small is the assimilation, 0°0015, during the gathering of 
the dense leaden clouds that preceded the storm. A higher number is 
reached during the bursting of the storm and the slow clearing up. 
