290 PROFESSOR MATTEUCCI'S ELECTRO-PHYSIOLOGICAL RESEARCHES. 



the pile, the muscular elements of which had been in carbonic acid, with another pile 

 similar to the former, but which had merely been left in contact with the air. After 

 having" opposed the two piles to one another, I have closed the circuit without ever 

 having found that any difference was induced by the carbonic acid. 



Summing up the results of the various and repeated experiments attempted in the 

 view of discovering the influence of some gaseous media (air, air greatly rarefied, 

 oxygen, hydrogen and carbonic acid) upon the intensity and duration of the muscular 

 current, we must conclude that this influence is either null or insensible, or in other 

 words, that the immediate causes of the development of electricity in the muscles re- 

 side in the muscular substance, independently of the gaseous medium in which it is 

 placed. 



In order better to determine the relation between the signs of the muscular current 

 and the organico-vital conditions of the muscle, since the last few months of the past 

 year I have directed my attention towards ascertaining the intensity of the muscular 

 current generated by a pile of half thighs of frogs, always made up of twenty elements. 

 I did this for the purpose of comparing the influence of the temperature of the me- 

 dium in which the frogs had lived, with the muscular current which they gave: I 

 will describe once for all and in a few words, my mode of experimenting. From 

 November 1844 to the end of March 1845, I have constantly sent twice a week to 

 have frogs caught from the same marsh. As soon as the frogs arrived at Pisa, they 

 underwent the usual mode of preparation for determining the intensity of their mus- 

 cular current. A certain number of these same frogs were put into a glass recipient 

 without water, and kept in a little room, the constant temperature of which was + 1 6° C. 

 (60°"8 F.) A similar number of the frogs were placed in a like recipient, but exposed, 

 on the terrace of the meteorological observatory, to the temperature of the atmo- 

 sphere. Lastly, four frogs taken from the mass were put into the bottle furnished 

 with a tube (fig. 3.), the tube AB of this bottle dipped in mercury. The apparatus 

 thus disposed was likewise left exposed to the temperature of the atmosphere upon the 

 terrace. In eight hours' time the tube C was opened, and inflating the bladder, a 

 portion of the air was collected, and the quantity of carbonic acid produced by the 

 four frogs in that time, and in those given conditions, determined. It is impossible 

 for me to relate all the experiments performed for the space of five months, twice a 

 week; comparing the frogs just arrived fresh from the marshes, with those kept for 

 twelve and twenty- four hours at a temperature of +16° C. I shall merely state some 

 of the numbers given by these experiments, in order to render the results of so many 

 experiments, all concordant, more evident. The temperature of the air, or of the 

 medium in which they live, the activity of the respiratory function, the intensity and 

 duration of the muscular current, are quantities which vary from one another pro- 

 portionally ; the temperature of the medium in which the frog lives cannot be raised 

 without occasioning an increase of activity in its respiration, and a corresponding 

 increase in the intensity and duration of the muscular current. 



