upon Respiration and Assimilation . 1095 
with that which took place in the dark, occurred. The highest readings 
from both leaves were approximately equal. 
The delay in the full development of the outburst of C 0 2 which took 
place in the darkened leaf here and in a few other cases seems most probably 
due to some diminution of rate of penetration of the chloroform. 
The leaves were still green at the end of the experiment. 
Experiment XVIII. Concentration of chloroform = 013 ex. per litre of 
air-current. The procedure was identical with Exp. XVII, but the con¬ 
centration of the chloroform was increased. The leaf in the light weighed 
3-55 grms., that in the dark 3-50 grms. The results are embodied in Fig. 20 
Fig. 20. 
and need no further comment, save that in this case both the leaves were 
brown at the end of the experiment and upon opening the leaf-chambers 
there was a distinct smell of hydrogen cyanide. 
Experiment XIX. Concentration of chloroform — 0*137 cx.per litre of 
air-current. This experiment followed a somewhat different course; a 
single leaf (weight 3*00 grms.) was illuminated for forty-four hours con¬ 
tinuously, being chloroformed after ten hours of illumination (Fig. 21). 
The readings taken before the chloroform showed that the leaf con¬ 
stantly assimilated all its respiratory C 0 2 (only the last appears in the 
figure). When the chloroform was introduced o*ooio grm. C 0 2 was given 
out during the next reading. Later, there was a very considerable but 
abnormally retarded outburst of C 0 2 , showing that the function of assimila¬ 
tion was completely arrested. 
Subsequently the output of C 0 2 fell fairly rapidly towards zero ; when 
