234 DRS. T. L. BRUNTON AND J. T. CASH ON CHEMICAL CONSTITUTION, 
1 to 3,000. Solutions of from 1 to 10,000 to 1 to 12,000 have both a slight power of 
counteracting the power of soda, and of lengthening the muscle; but 1 to 8,000 is 
the weakest dilution which is reliable for this purpose when applied externally. 
Normal salt solution has a distinct power of removing the shortening produced by 
soda, but its action is much more limited, and less complete than that of lactic acid. 
External application of dilute acids and alkalies to contracting muscle (Plate 9, figs. 25, 
26, 27). Soda and potash in solutions up to 1 in 8,000, or 1 in 10,000, cause a tonic 
shortening of the muscle, and may, at first, increase the height of its active contraction. 
Lactic acid in dilute solutions of 1 in 10,000, or weaker, may cause elongation to a 
muscle which has already soaked for some time in a salt solution. A solution of 
1 in 10,000 may cause at first a slight increase in the excitability and increased height 
of contraction, but this soon disappears. In dilutions between 1 in 8,000 and 1 in 
2,000 it causes eventually shortening of the muscle, with occasional fibrillation and 
rapid diminution of the extent of active contraction. At the same time that the 
contrantile power is diminishing, the muscle exhibits increasing viscosity. This is 
shown by a slight elevation of the basal line when the stimuli succeed each other 
with sufficient frecjuency. 
The permanent shortening caused by the application of an alkali is usually diminished 
by the subsequent application of lactic acid. After the diminution has occurred active 
contraction becomes feebler. 
Plate 9, fig. 25, shows the result of admitting soda solution 1 in 2,000 to 
the chamber containing a muscle which is being periodically stimulated through its 
nerve. (The solution almost entirely covers the muscle, but the nerve lying on the 
electrodes is above its level.) Plate 9, figs. 26 and 27, show the action of 1 to 4,000 
and 1 to 5,000 soda solutions on the acting curarised muscle. Here stimulation was 
of course direct, and the probable escape of current is therefore to be borne in mind. 
In both cases the subsequent action of lactic acid is shown, viz., a reduction of the 
basal line, and ultimately a fall in the altitude of the contraction. 
Action of Acids and Alkalies when circulated through the Muscle. 
The method employed was to pith and curarise a frog. A canula was then inserted 
into the aorta and connected with a branching tube, through which acid, alkaline, or 
salt solution could be supplied from a series of funnels. By elevating or depressing 
the funnels the pressure by which the circulation was carried on could be increased 
or diminished. Excepting when otherwise stated it was always effected at as low 
a pressure as possible. The condition of the muscle was registered by means of 
Marey’s myograph. The triceps was found to be the most convenient muscle for 
this series of experiments on account of its great vascularity. 
Moderately dilute solutions, both of acids and alkalies 1 to 4,000, after circulating 
for some time, caused the muscle to shorten. Galvanic stimulation to the muscle 
increases this effect, both of these solutions and also of weaker ones. It frequently 
