Stiles and J 0rgensen. — Studies in Permeability . V. 433 
of the facts of permeability, that a great amount of experimental work is 
needed before the presentation of fresh theories is justified. 
Summary. 
t. A method for investigating the passage of water between the cell 
and its surroundings is described, which is quantitative and allows the 
investigation of the kinetics of the changes taking place. 
1 . The probable error of experiment is determined, and the means of 
reducing it indicated. 
3. The tubers of potato and roots of carrot in distilled water absorb 
water (swell) for some days before equilibrium is attained. Equilibrium is 
maintained for a considerable time. 
4. The rate of swelling of carrot is much greater than that of potato. 
5. The previous history of the tissue influences greatly the magnitude 
of the swelling. 
6 . In tap-water, i. e. a weak solution of a number of salts, the magni- 
tude of swelling is less than in distilled water and equilibrium is not main- 
tained for so long (especially in the case of potato), a shrinkage of the tissue 
supervening. This is presumably due to the absorption of substances 
which cause an increase in permeability. 
7. Increase of temperature increases the rate of swelling. The 
temperature coefficients (Q 10 ) determined were, for carrot, about 1*5, and for 
potato, about 3-0. These are probably not definite values characteristic of 
the tissue, but probably vary with the previous history of the tissue. 
8. In solutions of sodium chloride and sucrose the swelling of potato is 
reduced with increase of concentration of the solution. With the sample of 
tissue used sodium chloride produced no swelling in a concentration of 
N M 
about — and sucrose in a concentration of about — . No swelling of the 
o 4 
N 
carrot used took place in a concentration of about — sodium chloride. 
3 
With concentrations above these values swelling took place ; with lower 
concentrations, shrinkage. The shrinkage obtained in these cases is identical 
with the shrinkage usually called plasmolysis. 
9. In the case of certain substances which enter the cell, such as the 
primary alcohols, preliminary swelling takes place in solutions of much 
higher concentration than isotonic solutions as determined by experiments 
with sodium chloride and sucrose. Subsequently shrinkage or depressed 
swelling occurs in all concentrations, which is correlated with the alteration 
of the permeability of the protoplasm and the death of the tissue. This 
shrinkage is due to toxic action and not plasmolysis. 
