68 D. Thoday. 
chloride, which accumulates first in the peripheral cells 1 * and only 
gradually penetrates to deeper layers. On the other hand, the more 
rapid entry of the M/100 solution than of distilled water suggests 
that the precipitation of proteins results first in a lowering of the 
resistance to the entry of water without making exosmosis of 
solutes possible, or at least a sufficiently rapid exosmosis to produce 
a counterbalancing reduction in the force under which water enters. 
A similar explanation would hold for M/1000 osmic acid. 1 The 
curves for this powerful fixative indicate a relatively small increase 
of permeability, and there is little or no evidence of this increase 
continuing progressively; but again further experiments are clearly 
required. 
Experiments were made with other substances, in addition to 
those already mentioned, but only a brief indication of the general 
nature of the results is warranted. The curves for solutions of 
copper sulphate were very similar to those for equi-molecular 
solutions of mercuric cyanide. Thus, with potato, the membranes do 
not oppose the passage of the former, like the coat of the barley 
grain, which differentiates sharply between it and the scarcely 
ionised mercuric cyanide. 3 
Phenol in concentrations of M/100 and M/1000 gave curves only 
differing from the curve for distilled water within the limits of 
experimental error; similarly M/1000 picric acid. Picric acid in 
M/100 concentration quickly started exosmosis, but the rate of fall 
in weight was as slow as with osmic acid. Alcohol in M/10 solution 
gave a curve which was nearer to that for distilled water even 
than M/25 sucrose, showing that it entered the cells readily, but 
without injuring the membrane appreciably in its relation to the sap 
solutes. 
Discussion of the general question of the osmotic relations 
between a tissue and solutions is reserved for a subsequent paper. 
Botanical Department, 
University of Manchester. 
February, 1918. 
1 See p. 61. 
3 Comparison with the more rapid swelling of proteins in acid solutions 
than in water does not appear to the writer helpful when the quantity of 
protein in the material is so small. Cf. Stiles and Jorgensen, V, loc. cit ., p. 
429 and 432. 
3 Adrian J. Brown, loc. cit., 1909, p. 88, etc. 
