1905. | The Structure and Function of Nerve Fibres. 335 
the condition of which is modified by injury and presumbably by excitation. 
When a more perfect state of colloid solution is degraded to a less perfect 
state, this fact is attended by a rise in osmotic pressure due to the liberation 
of electrolytes into a new condition of simple aqueous solution. The existence 
of a colloid solution with similar qualities in non-medullated nerve is 
inferred from the bulbar prominences, which at every site of injury form 
evidence of the effects of an increase in local osmotic pressure. Similar 
bulbar prominences occurring under similar conditions upon naked nerve- 
endings, and upon the dendrites of nerve-cells, point to the universal dis- 
tribution of such a solution throughout the whole scheme of nervous 
tissue. 
In explanation of this rise in osmotic pressure accompanying the observed 
degradation of the state of colloid solution, I will take it as possible that, in 
the colloid solutions here considered, a very considerable fraction of the mass 
of inorganic salts concomitantly present is situated upon the surfaces of the 
aggregates of colloid molecules. When, therefore, the total surface presented 
by such aggregates is increased by their more minute state of subdivision in 
the state of more perfect solution, the relative quantity of electrolytes locked 
up upon such surfaces may conceivably be increased, and the quantity in a 
state of simple aqueous solution diminished. On the other hand any 
desolution of the colloid may result in an increase of the quantity of 
electrolytes present in aqueous solution, and in a rise in osmotic pressure. 
Many instances are known of the collection of such a condensed solution 
of salts upon the surface of solid colloid masses, such as the surfaces of 
threads lying immersed in aqueous solutions of salts. It seems feasible that 
the conditions essential to their collection are also present when the solid 
masses of colloid material are infinitely reduced in size. The ocular 
demonstration of such a condition upon particles of visible size should 
not be difficult, and, indeed, may be obtained from an examination of 
Macallum’s drawings of the potassium ring surrounding granules within the 
nerve-fibre itself. It is possible, also, that Macallum’s observations of the 
collections of potassium upon the surfaces of certain tissue-cells may afford a 
demonstration of this condition present upon colloid aggregates of a larger 
size; and that the Golgi staining method, and all similar impregnation 
methods, may depend upon similar effects. 
Such an hypothesis carries with it the corollary, that the limited motion 
permissible to these electrolytes must diminish their usefulness in the trans- 
mission of an electrical current through the colloid solution. This corollary, 
therefore, opens up an objection to the hypothesis. The hypothesis would 
seem to be rendered unlikely by observations of the electrical conductivity of 
