492 
Seifriz.—Observations on the Reaction of 
killed in io per cent, ethyl alcohol within ten minutes,but in fifteen minutes 
several cells (o-i per cent.) die, and in twenty minutes i per cent, are 
killed. The percentage of cells killed then increases with the length of time 
of treatment. After 95 per cent, are dead the curve rises very rapidly, due 
to the great resistance of the few basal cells. All cells, including the basal 
ones, succumb in 10 per cent, alcohol overnight. 
Fig. 2. The curve depicts the average rate at which Elodea leaf cells are killed in a solution 
of 10 per cent, ethyl alcohol. The ordinates are minutes and hours of treatment. The abscissae 
are percentages of cells killed. Thus, o-i per cent, of the cells of a n Elodea leaf are, on the average, 
killed in io per cent, alcohol within fifteen minutes; 1 per cent, are killed in twenty minutes; 
60 per cent, in half an hour; 95 per cent, in two hours. The sudden rise of the curve is due to the 
great resistance of the few basal cells of the leaf, which usually require from six to twelve hours to 
kill in 10 per cent, alcohol. The curve is an ideal one based on many averages, the variations in 
resistance of different cells in a leaf, and of different leaves, being very great. 
The story of the toxic effect of alcohol on Elodea leaves can be told in 
another way. The curve in Fig. 3 represents the rate at which different 
strengths of solutions of ethyl alcohol kill the cells. The time in which a 
solution of alcohol would kill half the number of cells was chosen as a data 
upon which to plot the curve. By examining the curve one can ascertain 
how long an average cell may remain in an alcoholic solution of a certain 
strength and stand an even chance of surviving. Thus, in 5 per cent. 
