B4 PHYSIOLOGY AND TOXICOLOGY 



The heart pressure was now so slight, that I feared lest a clot might e.\ist in the trunk of 

 the artery, and therefore repeated the observations on the femoral artery, which gave at — 

 6.10 50 54 4 



rising in deep expiration to — 



67 

 6.15 53 56 3 



Still doubtful as to the correctness of the observation, I allowed a small jet of blood to 

 escape, and having thus made sure of the absence of clot, replaced the tube, and at once 

 marked at — 

 6.21 53 56 3 



The respiration was now labored and slow, the pulse being about 190. 



At 6.23, the artery was cut acros.'f, and the dog allowed to bleed to death. 

 Despite the slow and embarrassed bieathing, the blood ran red from the divided 

 vessel. It clotted very well in three to five minutes. The effect of the venom on 

 the force of the heart is well seen in the above stated experiments. In them, and 

 in other like observations, the power of the ventricular systole diminished very 

 rapidly soon after the bite, and at the same time, or just afterwards, the general 

 loss of tone was strikingly indicated by tlie diminution of the independent arterial 

 pressure. In the first case, the animal rallied from the early effect of the venom, 

 and the heart force increased, although not so much as to regain completely its 

 primary power. The cases just stated were selected from a series of seven similar 

 experiments, which I do not think it requisite to quote at length. In all of them 

 the results were the same in kind, although varying somewhat in degree. 



In most of these cases, the heart suffered somewhat before respiration was enfeebled 

 or visibly altered. But it was possible that the respiration might be embarrassed, 

 and yet not in so marked a manner as to betray itself to the eye. I thought it likely 

 that by destroying the normal respiratory infiueiice, and sustaining the heart by 

 insufflation, I might be able to place the cardiac organ in a condition which would 

 render it independent of any possible influence from the pulmonary organs. 



At first, I attempted to attain this end by cutting both pneumogastric nerves, and 

 thus destroying the main channels through which impressions originating in the 

 lungs are conveyed to the heart. My first experiments failed, owing to my having 

 used young dogs in whom the section of both nerves above the point at which the 

 recurrent laryngeal nerves are given off, never fails to cause asphyxia by collapse 

 of the lips of the larynx. To guard against this result, which, even in older ani- 

 mals, embarrasses the respiration, I placed a tube in the trachea, before dividing 

 the nerve trunks. The respiratory acts became immediately very deep and labored, 



