THE INJURY CURRENT OF NERVE 263 
If the electrical conductivity of nerve seems disappointingly small when it is 
sought to discover as its main function that of an electrical conductor, and when the 
prominence of the electrical phenomena discovered in it is considered, it is no longer 
so when a glance is taken at the known chemical constitution of the nerve. Thus, 
taking the figures collected in Halliburton's 1 article on the chemical constitution of 
nerve, sciatic nerves contain 61*3 per cent, of water and 38*7 per cent, of solids. 
The solids are given in the following estimation made from human sciatic 
nerve : — 2 
Solids of Human Sciatic Nerve 
Proteids ... ... 36 - 8o per cent of the total solids. 
Lecithin ... ... 32-57 
Cholesterin and fat ... i2 - 22 
Cerebrins ... ... 1 1*30 
Neurokeratin ... ... 3'°7 
Other organic matters ... 4/00 
99-96 
None of these bodies, which are arranged here, contributing to the solids of the 
nerve offer much prospect of a capability of acting as electrolytes: the only substances 
which would seem in this company to be characterized as such, the inorganic salts, 
are omitted from the table presumably from a failure to estimate the unimportant 
constituents. To form an estimate of the amount of inorganic salts present, we are 
compelled to use the quantity estimated as present in the white matter of the braiiu 
namely, "57 per cent, of the total solids, or in the spinal cord forming i*i per cent, 
of the total solids. 
These figures, while providing no exact guide, might lead us to infer that the 
inorganic salts of nerve formed '3 or '4 per cent, of its mass, a value which is sug- 
gestively similar to that of the total electrolytes as roughly estimated by the 
conductivity method. 
More point is given to these figures by the fact that the inorganic salts of nerve 
are not expressible as so much sodium chloride, a large quantity of potassium salt 
being also present, the electrical conductivity of which is greater. To explain the 
conductivity of nerve in terms of its inorganic salts, it is, therefore, necessary only to 
find present a quantity of these less than -3 per cent., and there seems every 
possibility of doing so. 
The small value of the electrical conductivity of nerve has long been appreciated, 
although few attempts have been made to exactly determine it. The fact in its gross 
form was, subsequently to the discovery of the electrical current by Galvani, made of 
1. Schat'er, Textbook I, p. 1 1 6. 
2. Moleschott, Physiol. C/iem., p. 335. 
