OF THE VENOM OF THE RATTLESNAKE. 83 



right femoral artery laid bare. The brass nozzle of M. Bernard's cardiomcter^ was 

 tied fast in the vessel, and the blood allowed to act on the column of mercury. 



At 4 o'clock, 58 minutes, the pulse being 99, and the respiration 21, the constant 

 pressure in the artery was found to be represented by eighty millimetres of the 

 column of mercury, which at every heart beat rose to 115 millimetres. 



The following record was then obtained : — 



Constant arterial Kising at each 



Time. pressure. heart beat to ' Difference. 



4.58 to 5.14 80-^ 115""" S-o-"" 



A clot forming, the column ceased to move. The tube was cleansed and replaced at 



5.16, when again a clot formed, and the artery was tied, and the left carotid laid bare. On 

 inserting the tube in this latter vessel, the record was as follows : — 



5.58 110 145 35 



6 



6.1 One large snake was allowed to bite the dog's left thigh. The dog struggled, and the mus- 

 cles about the wound quivered remarkably. 



6.4k 105 120 15 



Respiration perfect as yet. Heart pulse 115, respiration 22. 



6.6 95 115 20 



6.7 Pulse beats 120, respiration somewhat laborious. 



6.9 102 120 18 



6.10 105 115 10 

 A clot haviug formed, the tube was agaiu removed, cleaned, and replaced. 



6.19 85 105 15 



6.20 87 109 22 



6.21 85 110 25 



At this time a clot formed, and as some blood was lost in replacing the tube, the 

 observation terminated. The artery was tied, and the dog set at liberty. He was 

 very sick for two or three days, but finally recovered, surviving the ligation of two 

 arteries, and the bite of the snake. 



Experiment. — A yellow mongrel of middle size was secured as usual. About two 

 ounces of blood were lost while placing the tube in the carotid. At 5 o'clock, 

 30 minutes, the column rose to 114 millimetres, and at each heart beat to 127 

 millimetres, so that 13 millimetres represented the heart force. 



These figures remaining the same during two minutes, and the respirations being 

 26, and tranquil, the dog was bitten by three snakes, so as to be the more profoundly 

 afifected. 



* The cardiometer consists of a vessel, about three inches high, aud of the same diameter. A glass 

 tube, with a scale of millimetre divisions, passes down to the bottom of the vessel, and is open at both 

 ends. A second tube opens through the top of the vessel into its interior, and is provided with a stop- 

 cock. To its nozzle is attached a short oaoutchouc tube, which is terminated by a brass tube, made to 

 fit the artery selected for trial. The main vessel is now filled with mercury up to of the scale. The 

 caoutchouc tube is ne.xt filled with a strong solution of carbonate of soda, and secured in the artery. 

 The stopcock being turned, the mercury rises to a point which marks the lieight of a column of mercury 

 capable of being sustained by the constant pressure under which the blood circulates in the arteries. At 

 each heart beat, and at each deep expiration, the column rises a little, to fall anew, as the increased pres- 

 sure thus exerted is removed. 



