Permeability 83 
(3) A lessening of exosmosis as compared with the control on 
account of the action of the salt on the tissue. In the case of carrot 
exosmosis into distilled water is small, and if the action of the salt 
were to reduce it to nothing the results would be affected very 
little. 
Hence the method is not likely to give too high values for absorp¬ 
tion. On the other hand the following actions would tend to increase 
the conductivity and so render the observed measures of the absorp¬ 
tion too low. 
(1) Increased exosmosis resulting from the action of the salt on 
the tissues. This, long continued, leads to the death of the tissue 
(Stiles and Jprgensen, 1917 a) and consequently to loSs of its turgidity. 
But at the end of the experiments there was no loss of turgor of the 
tissues employed, so that it is unlikely the values obtained for 
absorption are appreciably raised on this account. 
(2) An unequal absorption of the ions of a salt as described earlier 
in this chapter. In this event it is the approximate absorption of the 
less absorbed ion that would be measured, for the excess of the more 
absorbed ion must be replaced by an equivalent quantity of a similarly 
charged ion, either H or OH from the water of the external solution, 
or by an ion escaping from the tissue, probably the latter (Redfern, 
1922 a). Moreover, as the mobilities of the absorbed and replacing 
ions will be different in all probability, and as a difference in the 
degree of dissociation may result, the fall in conductivity will only 
give an approximate value of the absorption. Owing to the possi¬ 
bility of this complication the results of Stiles and Kidd are therefore 
to be regarded as giving approximate values of the absorption of the 
less absorbed ions of salts. 
In the following table are shown the absorption ratios obtained 
for the absorption by carrot tissue of various chlorides from solutions 
possessing initially concentrations ranging from o-i N to 0-0002 N. 
The results with each salt are all strictly comparable, but the 
results with different salts should not be so compared as different 
batches of tissue were used for the experiments with each salt. 
If the logarithms of the final external concentrations are plotted 
against the logarithms of the final internal concentrations the points 
in the case of each salt lie approximately on straight lines. In Fig. 13 
the logarithms of the final external concentrations are taken as 
ordinates and the logarithms of the final external concentrations as 
abscissae. It will be observed that the relation is approximately a 
linear one in the case of each salt. 
6—2 
