428 Stiles and j0rgensen . — Studies in Permeability . V. 
4. Octyl alcohol 
In the preceding paper of this series it was shown how the complexity 
of the molecule in the series of monohydric alcohols influenced the exos- 
mosis of electrolytes. The higher the alcohol the lower is the concentra- 
tion which produces equal exosmosis. This relation ought also to appear 
in regard to the swelling of tissue in solutions of different alcohols ; that is, 
the higher the alcohol the lower should be the concentration required to 
produce the shrinkage which is correlated with exosmosis. 
This is found to be so, and the case of octyl alcohol, the most complex 
alcohol used, may be cited. It was previously found ( 17 ) that the ex- 
osmosis produced by a 1-4 M solution of ethyl alcohol was produced by 
a concentration of a secondary octyl alcohol 
CH 3 .(CH 2 ) 5 .CHOH.CH 3 
of 0-003 M. The swelling in three strengths of this alcohol are indi- 
cated in the following table. In o-ooi M the swelling is approximately 
the same as in distilled water. In 0-002 M the swelling is the same as in 
o-ooi M after one or two hours, but after sixteen hours the swelling is 
depressed just as in the case of 0-5 M ethyl alcohol. In a solution of concen- 
tration 0-003 PI swelling is the same after 1-3 hours, but by the end of 
sixteen hours there is a great shrinkage. 
Table IX. 
Swelling of Potato in Solutions of a Secondary Octyl Alcohol 
Time 
in Swelling in percentages of original weight . 
hours. 
o-ooo 
o-ooi M. 
0-002 M. 
0-003 M. 
i *33 
7-2 
7-2 
7*3 
7*4 
16-50 
16*9 
16-9 
i 3‘9 
— 19-2 
The form of the swelling curves given for ethyl alcohol may be regarded 
therefore as the typical form of such curves when the substance in solution 
outside the tissue enters the cell and produces changes which render the 
cell permeable to the solutes inside. 
5. Sulphuric acid. 
That alcohols enter the cell is not easy to show by direct measure- 
ment ; it is, on the other hand, comparatively easy to show by direct 
measurement that acids, or at any rate the hydrogen ions of their mole- 
cules, are readily absorbed by plant cells. This has been done in the first 
three papers of this series ( 15 , 16 , 8), and it has also been shown ( 14 , 8 ) that 
the absorption of the hydrogen ion is accompanied by the exosmosis of 
electrolytes from the cell. It would be expected then that the swelling of 
potato in acids would follow a similar course to the swelling in alcohols, 
that is, there would be a preliminary swelling, the magnitude of which 
