PHYSIOLOGICAL ACTION, AND ANTAGONISM. 
235 
happens that a muscle which exhibits little or no shortening before stimulation, 
becomes progressively shortened after a number of stimuli have been applied, until 
the basal line of the curve it describes is far above the normal. 
The pressure which is sufficient for the circulation of an acid solution, as a rule, 
quickly becomes insufficient to maintain the free circulation of an alkaline solution. 
This is to be expected from the fact that an alkali causes contraction of the involuntary 
muscular fibres of the vessels, and is in unison with Gaskell’s observation. 
The first effect of an alkaline solution, as a rule, is to increase the contractility of 
the muscle on stimulation ; the same stimulus producing a greater contraction than 
it would in the muscle without such circulation. A gradual shortening of the 
muscle, independently of any active contraction, is produced by the alkaline solution : 
this is shown by the rise of the basal line in the curve. After the circulation has 
been maintained for some time, both the contractile power and the irritability of the 
muscle decrease; the height of the contraction occurring on stimulation not being so 
great, and a stronger stimulus being required. 
Plate 9, fig. 28, a , 6, c, is introduced to show the fibrillation and temporary 
shortening which may occur upon the first stimulations of a muscle through which 
lactic acid has been some time circulated. 
Plate 9, fig. 29, a, b, c, shows that the elevation of the basal line, caused by the 
circulation of soda (1-20,000), is to a large extent reduced by the subsequent cir¬ 
culation of lactic acid 1-10,000. The altitude of the contraction is likewise reduced. 
Lactic acid, when circulated through the muscle, frequently causes fibrillation, and 
at first shortening of the muscle after fibrillation : there may, however, not be any 
shortening. 
Usually the height of the contractions diminishes rapidly on repeated stimulation ; 
sometimes, though quite exceptionally, the irritability of the muscle is increased at 
first, and the contractions resulting from stimulation may be at first more extensive 
than those of the normal muscle. 
(Edema of the muscle is occasionally observed as a consequence of the circulation of 
acid through the vessels ; this is unusual after the circulation of alkalies. The impaired 
contractile power eventually produced by the circulation of either alkali or acid 
through a muscle may be restored to a greater or less extent by the circulation of a 
fluid having an opposite reaction. The completeness of the restoration depends upon 
various circumstances, amongst which we may mention the cedematous condition of the 
muscle, which we have already noticed as occurring from the circulation of acids. 
Our experiments on the muscles of the Frog have thus shown a very marked 
antagonistic power between acids and alkalies, or perhaps to speak more definitely, 
between solutions of potash or soda and lactic acid. It seemed advisable to make 
some experiments on the muscles of warm-blooded animals, in order to discover 
whether the same antagonism was to be found in them : for this purpose we chose 
the gastrocnemius of the Cat. The solution to be investigated was warmed to 40° C, 
2 h 2 
