2.36 DBS. T. L. BBTJBTON AND J. T. CASH ON CHEMICAL CONSTITUTION, 
and then passed through the limb by means of a canula inserted into the femoral 
artery. The muscle was stimulated from the sciatic nerve, the leg being' previously 
fixed by a clamp. The muscle was extended by a weight of 40 grammes attached 
by a cord working over a pulley ; this was allowed to remain constantly attached in 
some experiments to ascertain alterations in the length of the muscle due to the fluids 
circulated. In several cases it was applied for two minutes before each tracing. 
Plate 9, fig. 30, shows the effect of acids and alkalies. 
(a.) The lever recorded (multiplies 4 times) contractions of 12'5 millims., an opening 
and closing shock every 4". 
(b.) After alkali 1-20,000 had circulated 10 m the basal line showed a shortening of 
8 millims. The active contraction was 13 millims. Ten minutes after this tracing 
had been taken the flow, which had previously been free from the femoral vein, 
became very slow, and remained so under a considerable increase of pressure. 
(c.) Lactic acid 1-10,000 restored the circulation and reduced the contraction. The 
active contraction of the value of 12 millims. 
(cl) Alkali circulated 20 m has raised the basal line 10'5 millims., but shows an active 
contraction of less than 10 millims. 
( e .) After 60 m circulation the basal fine is still 10’5 above the normal, but the active 
contraction has increased to 11*5 millims. 
There is here, then, a great similarity of action in the case of acid and alkali 
circulated through the vessels of cold and warm-blooded animals. 
General Results of Experiments on the Action of Acid and Alkali on Muscle. 
The experiments just described show that dilute alkalies, potash, and soda cause 
shortening of muscle, which is antagonised by dilute solution of lactic acid. Since 
the preceding section of this paper was sent in to the Royal Society we have made 
some further observations on this subject, and from an examination of the curves 
it will be seen that, by the alternate application of alkali and acid, a muscle may be 
made to describe on a slowly revolving cylinder a curve very nearly resembling that 
described on a rapidly revolving cylinder by a normal muscle when stimulated. Other 
tracings show that this curve may be modified very nearly at will by altering the 
proportions and duration of the alkali and acid. Curves may be thus described which 
resemble those drawn by muscles stimulated after they have been poisoned by barium, 
rubidium, and other substances of the groups we have examined. In these curves we 
see produced by varying the application of the opposing solutions the same prolonged 
contraction, the tendency to an exaggerated secondary hump, and increased contracture. 
We cannot at present draw from this a definite conclusion, but it is suggestive of 
the question—Does the normal contraction of muscle and its subsequent relaxation 
depend upon such alterations in its saline constituents as to make them play at one 
time the part of an alkali, and at the other the part of an acid \ 
