120 



of the ascension of mercury in the hemadynamometer is, the in- 

 crease in the force of the heart. A simple experiment proves 

 that I am right. I adapt the hemadynamometer to the aorta in 

 the abdominal cavity, and then I open quickly the chest, and I 

 put a ligature to the brachial and carotid arteries. About three 

 quarters of a minute after opening the chest, and about half 

 a minute after the ligature has been put on the arteries of the 

 head and arms, the mercury rises notably in the instrument ; 

 sometimes the elevation is as considerable as two inches. It re- 

 sults from this experiment, that the heart beats more strongly in 

 asphyxia about one minute after its beginning. 



d. Woodall, a most intelligent and accurate observer, says Dr. 

 Martin Paine, (see Med. and Physiol. Comment., t. ii. p. 49,) 

 states, that the best remedy for syncope is to obstruct respiration 

 entirely by momentarily confining the nose and mouth. If this 

 be true, it is in perfect accordance with my view, that, during as- 

 phyxia, the normal cause of the beating of the heart increases in 

 the blood. 



e. If a frog is put under a receiver containing pure oxygen, at 

 a temperature of 40 or 50 Fahr. (4, 5, or 10 Cent.) after its 

 heart has been laid bare and its central nervous system destroyed, 

 we see the heart beat for a very long time, (one, two, or three 

 days.) On the contrary, if, at the same temperature, another 

 frog, deprived also of the central nervous system, is put in car- 

 bonic acid gas, the heart beats very quickly at first, but it soon 

 ceases to beat, (in one or two hours only, sometimes, and for the 

 most about half a day.) 



/. All the causes which increase the formation of carbonic acid 

 gas in the body, increases the frequency of beatings of the heart. 



g. If we inject the serum of blood into the arteries of the heart, 

 so as to expel as completely as possible the blood contained in the 

 capillaries of this organ, and if then we remove the blood from 

 the cavities of the heart, we find that its beatings are, at once, 

 almost entirely suspended, and that they are completely stopped 

 in a very short time, (from one to eight minutes.) The muscu- 

 lar irritability is not destroyed in this organ ; it does not beat 

 because its excitant has been removed. 



h. I have found that when the heart of a young animal is put 

 in hydrogen, its beatings hardly change at first, but they stop in 



