Notes . 
417 
five minutes. The chloroform appears at first to exercise a physical 
action favouring the formation of gas-bubbles, and the heating effect 
of the sun’s rays may also aid in causing an evolution of bubbles after 
the plant has been fatally injured, for after five minutes immersion the 
plants have lost the power of recovery and rapidly die in fresh water. 
By using more dilute proportions and longer periods of exposure it is 
possible to cause a cessation of C 0 2 -assimilation without the power of 
recovery being lost. 
Elodea canadensis, (a) Plant exposed to sunlight in water at 18 0 C., 
super- saturated chloroform-water allowed to trickle slowly in, and the 
water gently agitated. Evolution of bubbles slows after \ hour and 
ceases in 1 hour. Water rises to 28° C. in this time, and hence 
intercellular air (-§- c. c.) is increased by J c. mm. in volume, an 
appreciable fraction of the total amount of gas evolved but probably 
partly compensated for by the increased respiratory activity. Leaves 
washed and immediately examined, show no rotation, no evolution of 
oxygen, and the chloroplastids do not take an apostrophic position in 
strong light. Next day the plant shows feeble evolution of gas-bubbles : 
on examination about half the leaf-cells and nearly all the stem-cells 
are living and show with the bacterium- method a moderately active 
evolution of oxygen, which in a few cases is feeble or doubtful. 
(d) Experiment repeated with plant in water at 2 7°C., evolution of 
bubbles slows in 10-15 m in. an d ceases in 20-25. Plants immediately 
washed and placed in fresh water show no evolution of bubbles after 
3 hours, but occasional bubbles after 5 hours ; while a leaf when first 
examined shows no rotation, no evolution of O, and the chlorophyll- 
grains remain dispersed in strong light, in 3 hours there is faint to 
moderately active evolution of oxygen and the chloroplastids assume 
the apostrophic position. Next day moderately active evolution of 
bubbles is shown, and most of the leaf-cells remain living and show 
active rotation. 
These results therefore confirm the original experiments by 
Cl. Bernard, and show that a stoppage of C 0 2 -assimilation may 
be produced by uniformly distributed anaesthetization if properly 
graduated to the resistant powers of the plant employed. 
A. J. EWART. 
Botanical Laboratory, Oxford. 
