500 Seifriz.—Observations on the Reachoti of 
writer (21) with SrCl 2 . The writer has found that SrCl 2 causes an increase in 
permeability and not, as Osterhout maintains, a decrease. This conclusion 
is based on the assumption that a lower critical concentration of plasmolysing 
salt indicates increased permeability. It becomes important, therefore, to 
ascertain conclusively whether or not there has been an increase , as the writer 
believes, or a decrease in permeability of the protoplasmic membrane when 
the critical plasmolysing concentration is lower as a result of treatment. 
This was accomplished for smilacin-treated cells by the following experi¬ 
ment. 
If, as a result of treatment, there has been no alteration in the permea¬ 
bility of the plasma membrane, then smilacin-treated cells should prove to 
be no more sensitive to alcohol than normal cells. If permeability has 
decreased , then the treated cells should actually be less susceptible to the 
toxic effect of alcohol. If, however, permeability has been increased by 
treatment in smilacin, as the writer believes a decrease in critical plasmo¬ 
lysing concentration indicates, then the treated cells should be more sus¬ 
ceptible to alcohol than untreated ones, since the increased permeability of 
the treated cells will permit a more ready entrance of the alcohol. 
Leaves which had been in a 0-5 per cent, solution of smilacin for 
eighteen hours were treated with 10 per cent. KNO., to ascertain the number 
of cells killed by the glucoside. The average number of dead cells was but 
o-8 per cent, of the total. Other leaves which had undergone the same 
treatment in smilacin for eighteen hours were, together with some control 
leaves, put in 10 per cent, alcohol for ten minutes. By referring to the 
curve in Fig. 2 it will be seen that ten minutes in 10 per cent, alcohol is not 
sufficient time to kill any cell in a normal leaf. This was true of the con¬ 
trol leaves above mentioned. The cells of the smilacin-treated leaves , how¬ 
ever , succumbed to the extent of 92 per cent, as the result of a ten-minute 
treatment in alcohol. A similar experiment was performed, keeping the 
saponin-treated and the untreated leaves in 10 per cent, alcohol for twenty 
minutes. Seventeen per cent, of the cells were killed by alcohol in the 
control leaves. In the smilacin-treated leaves 95 per cent, of the cells zvere 
killed by the alcohol. The evidence seems conclusive that the plasma 
membrane is a more open one (since it is more permeable to alcohol) in 
smilacin-treated leaves than in normal leaves. 
Further proof of a more permeable membrane as the direct effect of 
these glucosides on the plant cell is to be had from another observation. 
It was frequently observed that the chloroplasts of smilacin-treated cells 
suddenly scattered, just as if a miniature explosion had taken place within 
the cell, after the addition of potassium nitrate and before plasmolysis 
occurred. This is due undoubtedly to the effect of the salt which rapidly 
enters the smilacin-treated cell through its more permeable membrane. 
Another phenomenon which adds further proof in support of the fact 
