Exosmosis. 
74 Stiles and J0rgensen . — Studies in Permeability. IV. 
from which, integrating between limits, we have 
u 
S-. 
u + v 
log 
u + v\ 
tl 
S 
- At 
')}> 
which may be written in the form 
-2?log(i-fe) = D(±*~ M + i-±), 
where j is the concentration of the external solution at any time t and 
A, B, D and k are constants depending on the concentration of the external 
solution, the quantity of tissue used, and the volume of solution. 
The curves given by this equation are of the same form as those 
obtained by us for the exosmosis of electrolytes from plant tissue. In the 
accompanying figure we give the curves obtained in which the constants B , 
Time. 
Fig. 15. Curves obtained from theoretical considerations of the relation between time and 
quantity of exosmosis from plant tissue. 
D, and k are put equal to unity, and A y which depends on the concentration 
of the external solution, is given different values. A comparison of these 
curves with those for the higher concentrations of each substance experi- 
mented with will show how similar they are. 1 
It will be observed that the curve consists of three regions : first 
a region in which the rate of exosmosis is gradually increasing, then 
1 The system is certainly more complex than we have assumed here. For instance, we have 
neglected the rate of diffusion of substances in the system. In thick discs and cylinders of tissues 
this becomes a very important factor, as some of our unpublished researches show. The equation 
given can only be considered a very rough approximation. 
