7 ° 2 
Thoday . — On the Effect of Chloroform on 
complete. The fresh leaves soon regained their normal intensity of respira- 
tion. In the starved leaves of Experiment 1 1 , on the other hand, respiration 
was maintained at the high level for several days. Other similar experi- 
ments with starved leaves, though not all, showed a similar relatively 
persistent augmentation of the respiration ; what the exact conditions may 
be which determine this interesting effect is not yet clear. 
Experiment III. July i 6 , 1909. Dose, 0-3 c.c. for sixteen minutes. 
Temperature, 18-20° C. 
The six leaves used had been gathered two days previously. The rate 
of respiration before chloroforming had fallen a little below that of other 
similar leaves newly gathered. 
In this experiment the dose was the same as in the previous experi- 
ments, but more chloroform appears somehow to have penetrated into the 
leaves during exposure ; for, 
although no change was 
visible before they were 
put into the respiration 
chamber, at the end of 
six hours small chocolate- 
coloured spots were found 
on them, showing that in 
these places the cells were 
completely disorganized. As 
before, the respiration was 
augmented ; it reached a 
greater maximum intensity 
than in Experiment I, and 
remained at a high level 
much longer, though not so long as in Experiment II. It appears that 
the rate of production of C 0 2 rose slightly above the rate of absorption of 
oxygen, and was so maintained for about six hours ; the respiratory quotient 
thus rose from about 0-9 to about 1-03. In the subsequent slow fall the 
0 2 intake fell more slowly than the C 0 2 output, so that eventually the 
original respiratory quotient was reached again. 
In the next two experiments the dose of chloroform was large enough 
to be followed by complete disorganization. The first sign of the change 
was already visible as a uniform faint brown tinge when the leaves were 
removed from the chloroforming vessel, and the brown coloration rapidly 
deepened during the period of enclosure in the respiration chamber to 
a uniform chocolate brown. The first faint tinge of brown is always, as far 
as my observations go, a sign that irreversible changes have begun from 
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HOURS AFTER CHLOROFORM 
26 
Fig. 4. 
