
1905. | The Structure and Function of Nerve Fibres. 33] 
The acid character of his reagent is in itself a ground for assuming that this 
is the case. Let us suppose that the fibre was excited toa state of contraction 
by the acetic acid contained in his reagent; that the process introductory to 
contraction was the sudden liberation of inorganic salts into a state of simple 
solution; that the facts of contraction were due to the new conditions of 
osmotic pressure so produced. The liberated salts being immediately precipi- 
tated by his reagent, it might even happen that such a train of events could 
occur without any of the external manifestations of the contracted state being 
observed. 
Again, Macallum has depicted similar strong solutions of potassium salts as 
present in the units of structure responsible for the flow of water in the sap 
of plants. He describes these solutions as the passive relict of previously 
transmitted solutions of potassium. Such solutions are supposed to have 
passed through; the water has evaporated, and cumbersome collections of 
salts have been left behind. Here, again, however, it must not be lost sight 
of that these salts were in a state of solution when precipitated by his 
reagent, and were therefore capable of exerting their due value of osmotic 
pressure. It seems possible in this case also that he was dealing with an 
excited tissue; that these regions of high osmotic pressure represent the 
cause of the transmission of water, and not its after consequences. 
REFERENCES. 
1. J.S. Macdonald, ‘Thompson Yates Laboratory Reports,’ vol. 4, Part II, pp. 213—348, 
1902. 
2 ‘Proc. Roy. Soc.,’ vol. 67, pp. 315—324. 
3. ‘Proc. Roy. Soc.,’ vol. 67, pp. 325—328. 
5. : ‘Proc. Physiol. Soc.,’ December 17, 1904. 
6. ‘Proc. Physiol. Soc.,’ March 18, 1905. 
Te A. B. Meal at, ‘ Journal of Physiology,’ vol. 32, p. 1. 
ADDENDUM—Received May 13, 1905. 
Summarising in a former paper (+) all the evidence then obtained as to the 
distribution of inorganic salts in nerve-fibres, I made use of a statement from 
which perhaps a quotation might now be permitted. Since, for purposes of 
criticism, it clearly defines the personal point of view from which this present 
investigation was undertaken. “ Accepting all that is taken as known of the 
minute microscopical structure of nerve, there is no inherent improbability in 
the supposition that the inorganic salts of the nerve might be there held 
enchained in a highly concentrated solution free to move parallel, but not at 
right angles to and away from the fibrille. Granting such a possibility, we 
are however faced by the important corollary that such concentrations are 
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