PHYSIOLOGICAL ACTION, AND ANTAGONISM. 
237 
Plate 9, figs. 31 and 32, show the relative effects of solutions of 1 to 3,000 caustic 
soda solution (Plate 9, fig. 31) and caustic potash solution (Plate 9, fig. 32) upon 
resting muscle. The tracings were taken upon a slowly revolving cylinder. Each 
centimeter of the tracing represents 5 m . The lever, which multiplies fourteen times, 
exercises a constant traction of 10 grms. on the muscle. Fresh solution was added 
where stars are placed in the course of the curve. It will be seen that the shortening 
effect produced by caustic soda in 50 m , during which the solution was renewed every 
10 m , is slightly greater than is the case with the companion muscle treated with 
caustic potash of the same strength. The curves, however, show a very close similarity 
throughout. The commencing relaxation caused by the substitution of 1 to 1,000 
lactic acid is seen in each case. 
The very gradual shortening of the muscle upon the first application of potash 
and soda is, to some extent, due to the fact that the muscles had been previously 
curarised. When curara has not been previously employed the first application of 
dilute solutions causes a more rapid primary contraction, though the total effect of 
the application may not be greater, if as great as in the curarised muscle. Plate 9, 
fig. 33, gives the effect of a stronger solution of soda, i.e., 1 to 2,500, and the sub¬ 
sequent relaxation it undergoes upon the application of 1 to 500 lactic acid, 
Plate 9, figs. 34 and 35, give the action of soda 1 to 4,000, and potash 1 to 6,000, 
with partial relaxation consequent to lactic acid. That lactic acid itself causes 
shortening, if of a certain strength, is shown in Plate 9, fig. 36, when 1 to 1,000 
solution of the acid causes in 25 m a shortening of 4 millims. in the curve, or of 
*3 millim. in the muscle. 
The application of potash reduces this shortening to some extent, and then, its 
own action being no longer balanced, causes the muscle to contract rapidly. The 
converse of this is seen in Plate 9, fig. 37, when the alkali is first applied, and the 
acid 1 to 500 causes a relaxation, and then a shortening of its own. To cause a 
complete relaxation a higher dilution is necessary. 
Plate 9, figs. 38 and 39, give tracings of passive shortening or lengthening with an 
active contraction (maximal stimulation) taken at intervals superimposed. 
Plate 10, fig. 40, a, b, c, illustrates the change of form the normal muscle curve 
undergoes when treated with an alkali local application. The first “ hump ” of the 
active contraction is increased in altitude; the second “ hump ” or elevation after 
the notch is reduced. Owing to this reduction the curve is shortened. A passive 
shortening of the muscle is seen at c, and is, in point of fact, less than is usually 
produced by solutions of these strengths. 
The effect of lactic acid applied in the same manner is shown in the series a, b, c. 
Plate 10, fig. 41. Here also the second portion of the curve is reduced, and the 
relaxation becomes much more rapid. After 60 m in lactic acid 1 to 2,500, a slight 
contraction of 1*5 millim. is observable. 
Plate 10, fig. 42, a, b, c, cl, e, gives the action of potash on the normal muscle, to a 
