232 Hind.— Studies in Permeability. HI. 
The experiments described above show that considerable difference 
exists between acids, even in dilute solution, as regards their action on plant 
cells. The mineral acids on the one hand cause much less exosmosis, and 
presumably therefore produce much less injury than the two fatty acids 
employed on the other. Oxalic acid appears to occupy an intermediate 
position. 
The earlier work referred to in the introduction to this paper is not 
therefore absolutely confirmed. Support is given to the contention that 
with organic acids the anion influences the action on plant cells, but, having 
regard to the different results with hydrochloric and nitric acids, it must be 
supposed that even with these the anion also has an effect. However, the 
acids containing ‘ nutrient ’ ions such as S0 4 and N0 3 , as well as hydro- 
chloric acid, are sharply marked off from the fatty acids in respect of their 
power of producing exosmosis from the tissues. 
A further conclusion which may be drawn from the curves given in 
this section, is that the rate of absorption of an acid depends on its 
