PHYSIOLOGICAL ACTION, AND ANTAGONISM. 
233 
Further, by regulating the height of the fluid the nerve can be exposed to the 
action of the solution, or kept free from it. The chamber is enclosed by a belt (m) 
connected with a rod, which fits into a nut sliding up and down on a steel upright. 
The lever is connected with the muscle in the usual manner, and its axis moves, 
together with the chamber, upon the rod of which it is clamped. By certain modifica¬ 
tions this chamber is heated or cooled, so that the effects of variation of temperature 
upon the poisoned muscle may be easily studied. It is also possible to test the 
effect produced not only by hot and cold air, but by solutions gradually heated or 
cooled to any desired extent. 
As already mentioned, the apparatus serves the purpose of testing the effect of 
gases and vapours on muscles very satisfactorily. 
This mode of application was chosen on account of the obstacles to the circulation of 
alkalies in the muscle, and also because Yon Anrep'"' asserts (l) that the action of 
a solution thus locally applied is the same as when the solution has been made to 
circulate through the tissues. Gaskell has privately communicated to us the same 
result, and numerous experiments of our own have confirmed these statements. 
Yon Anrep, in investigating the action of potassium upon muscle, found that it 
caused, either when applied locally or through the circulation, a decided shortening of 
the muscle, which in a few minutes reached its maximum. This shortening is inde¬ 
pendent of the action of the spinal cord, for it occurs whether the muscle remains in 
connexion with the cord, or whether the nerves be cut. The shortening has no relation¬ 
ship to the irritability of the muscle. The irritability of a muscle through which a 1 per 
cent, solution of potash is circulated for fifteen to twenty minutes is quite abolished, 
while the shortening persists; occasionally a slight elongation is seen, in place of a 
shortening. On the other hand, he found that sodium has not this effect on muscle. 
Effects of Acid and Alkali applied externally to Muscles at rest. 
Dilute solutions of potash and soda, containing from one part in 4,000 to one 
part in 8,000, cause shortening of the muscle. The contraction produced by soda 
was slightly greater in our experiments than that caused by potash, the solutions 
applied being of equal strength, and for an equal time. 
Lactic acid, in very dilute solution of 1 to 8,000 or more, seems to tend to elongate 
muscle which is loaded with a slight weight. 
A solution of chloride of sodium alone, however, also causes relaxation of the muscle, 
and the continuous application of a slight weight has a similar effect. 
Less dilute solutions of lactic acid, 1 in 4,000 or stronger, causes passive shortening 
of the muscle, and this is occasionally accompanied with fibrillary twitchings. Dilute 
solutions of lactic acid cause relaxation of the muscle which has been shortened by 
potash or soda. 
There is a fairly balanced antagonism between lactic acid 1 to 8,000, and soda 
* Pfluger’s Archiv., vol. xxi., p. 226. 
2 H 
MDCCCLXXXIV. 
