49 ° 
Seif) 'iz.—Observations on the Reaction of 
cent, by weight are not harmful to the plant cell after a long time ( 18 , 
p. 105). One would, therefore, expect no harm to result from a 3 per cent, 
solution of alcohol, and relatively little from a 10 per cent, solution, after 
no more than a few hours of treatment. Quite the contrary, however, is 
true. A ]o per cent, concentration of ethyl alcohol is sufficiently strong to 
kill, on an average, 60 per cent, of the cells in an Etodea leaf within half an 
hour, 80 per cent, of them within an hour, and 95 per cent, within two 
hours. A 3 per cent, concentration of alcohol will kill, on an average, more 
than half the number of cells in from four to six days. If the cells of the 
Etodea leaf are unusually sensitive to alcohol, a 2 per cent, concentration 
will kill 50 per cent, of them in less than two days. 
An interesting fact in connexion with the toxicity of alcohol on protoplasm 
is the variability in sensitivity of cells both in the same leaf and in different 
leaves. It was a common instance 
to find a dead cell, killed by the re¬ 
agents, next to an actively streaming 
one, and to find certain cells which 
would withstand the poisonous effect 
for twenty-four hours while others in 
the same leaf succumbed in half an 
hour. 
The dead cells are usually 
grouped in patches, suggesting a 
common physiological state before 
death in these regions. The less 
resistant cells may be grouped into 
two blocks situated in similar posi¬ 
tions on each side of the leaf (a, 
Fig. 1); or the cells in one entire 
Fig. 1. Diagrammatic sketches indicating 
those regions of an Elodea leaf which first 
succumb to the toxic effect of ethyl alcohol. 
A. The cells killed may, as result of brief 
treatment in io per cent, alcohol, be situated in 
two blocks occupying corresponding positions on 
opposite sides of the midrib sharply delimited 
from the remaining leaf area of living cells. 
B. The dead cells, after longer treatment, may 
occupy the entire half of the leaf. c. The typical 
distribution of living and dead cells of a leaf 
treated for one hour in 10 per cent, ethyl alcohol. 
The verv basal cells are the last to succumb. 
half of a leaf may be killed while those in the other half remain alive and 
apparently normal (b, Fig. 1). In leaves treated in 10 per cent, alcohol, 
which kills quickly, there are definite regions which are in all cases more 
or less resistant to the alcohol. The few cells situated at the base of the 
leaf, extending a little way up each edge and still farther up the mid-rib, 
are the last to succumb to the toxic effect of 10 per cent, ethyl alcohol 
(c, Fig. 1). So pronounced is this difference in resistance that, while all 
the other cells, i. e. 95 per cent, of the total, may sometimes, in a more 
sensitive leaf, be killed in half an hour in 10 per cent, alcohol, it requires 
six hours or more of treatment to kill the two or three hundred cells 
situated in the base of the leaf. On the other hand, the alcohol-resistant 
basal cells are as sensitive as any in the leaf to some other reagents, e. g. 
to strontium chloride. 
This variability in behaviour is not only true of different cells in a leaf, 
