MR. J. PRIESTLEY ON THE PHYSIOLOGICAL ACTION OE VANADIUM. 551 
stimulated with single induction-shocks from a Du Bois-Reymond’s machine, the opening 
shock being used. The battery consisted of a single Daniell’s element. The maxi- 
mum stimulus was ascertained in the usual manner, and employed to produce con- 
tractions. 
The second frog was allowed to remain until five hours had elapsed from the time of 
injection, and more than three from the occurrence of complete motor paralysis. 
The curves obtained by taking the weights of the load as abscissae and the length of 
contraction as ordinates were found to be sensibly the same in the case of poisoned and 
non-poisoned muscles, as is shown in fig. 4, Plate 46. 
The experiment was repeated with similar results. 
Exp. LXXIX. — June 1875. 
In this experiment preparations were made for recording upon a revolving surface 
the contraction of muscles when directly stimulated. 
The arrangements for stimulation resembled exactly those in the preceding experiment. 
Three frogs were again taken, and two poisoned by the subcutaneous injection of 
1 cub. centim. of a 5 per cent, solution of sodium vanadate (=50 milligrammes V 2 0 5 ). 
They were allowed to remain until four hours after injection and two hours after com- 
plete motor paralysis. They were then arranged in a myograph and weighted with 
10 grammes. 
Both opening and closing of the primary current were made use of. 
The normal frog was decapitated, and allowed to remain for two hours before being 
tested. The curve of its contraction was then obtained in the above-mentioned manner. 
Rotation of the revolving surface was checked and time recorded by means of the vibra- 
tion of a tuning-fork vibrating 100 times per second. 
The curves obtained in the cases of poisoned and of non-poisoned muscles were sen- 
sibly the same, as is shown in fig. 3, Plate 45. 
The experiment was repeated with similar results. 
The preceding two experiments are considered to show that vanadium in the form of 
sodium vanadate does not affect muscular tissue when introduced into the circulation of 
living animals. 
It has been shown in a previous part of this research that the disturbance of circula- 
tion and respiration which follow poisoning by vanadium are mainly due to an action of 
the poison upon their respective centres in the cord. It seems, therefore, of interest to 
give here, among the experiments relating to the nervous system, some which show the 
simultaneous action of the poison upon circulation and respiration. 
