Protoplasm to some Reagents. 501 
that a greatly increased permeability of the plasma membrane results from 
treatment in the saponins, is the sudden collapse of smilacin-treated cells 
after slight plasmolysis has taken place following the application of the 
plasmolysing salt. 
In attempting to obtain the critical plasmolytic concentration of cells 
treated in 0-5 per cent, smilacin, the immediate plasmolysis of many cells is 
often recorded, but on observing the leaves at the expiration of the half-hour 
period no plasmolysed cells are to be seen. Their collapse, i. e. a sudden 
return of the plasmolysed protoplast to its original size, was subsequently 
observed. The resulting protoplast was a much disorganized one. This 
collapse was less often observed in saponin and senegin treated cells, but was 
the rule in smilacin-treated cells. 
Of fifteen smilacin-treated cells observed (after twenty-one hours in 
a 0*5 per cent, solution) all plasmolysed to a moderate degree after four 
minutes in 4 per cent. KNO,. Then one plasmolysed protoplast suddenly 
collapsed. In five minutes five out of the fifteen protoplasts had collapsed. 
In nine minutes all had collapsed. This can only be interpreted to mean 
that the salt had entered at an abnormally rapid rate through a very porous 
membrane, and caused complete disorganization. 
A fact worthy of note in connexion with this sudden collapse of smilacin- 
treated cells is that the collapse was only obtained with a low percentage of 
salt, slightly above the critical concentration, and never with a high per¬ 
centage of salt. One might expect a more abundant entrance of ions through 
the open membrane from a jo per cent. KNO., solution than from a 4 per 
cent, solution, yet this was not true. Smilacin-treated cells plasmolysed 
with 10 per cent. KN 0 3 never collapsed. The explanation is clear. The 
4 per cent, salt entered freely without causing any change in the very per¬ 
meable membrane. The 10 per cent, salt, on the other hand, coagulated 
the dilute membrane, thus instantly decreasing its permeability and pre¬ 
venting the subsequent entrance of the salt. 
The great readiness with which alcohol and potassium nitrate enter the 
protoplast of smilacin-treated cells is evidence of a much more permeable 
membrane in these cells, thus substantiating the interpretation that a decrease 
in critical plasmolytic concentration means an increase in permeability. 
That saponin markedly increases the permeability of a protoplast is 
also the belief of Boas ( 3 ), who arrives at this conclusion from experiments 
of an entirely different nature than those of the writer. Boas subjected 
oats to a 5 per cent, solution of saponin for twenty minutes, then placed 
them in 25 per cent, cane sugar and measured the amount of carbon dioxide 
formed. In two hours the saponin-treated material had produced three 
times the amount of carbon dioxide that the control material had, and in 
six hours’ time twice as much. The increase in fermentation of the sugar 
is a result of increased permeability of the cells. 
