ACTION OF AMYL NITEITE ON PULMONARY CAPPILLARIES. 369 



remedies we employ, our treatment must be empirical, and suc- 

 cessful results must be our warrant for employing one method 

 rather than another. The second indication, viz., to dilute the 

 blood, is generally fulfilled by giving ice and ice-cold water by 

 the stomach. The wonderful effects which immediately follow 

 injection of salt solutions into the veins show what an important 

 share the loss of water from the blood has in the production of 

 collapse. The ultimate benefit resulting from this mode of treat- 

 ment has hitherto not been commensurate with the immediate 

 relief to the symptoms which it affords, but this should only 

 lead us to try whether we cannot, by employing different pro- 

 portions of salts, or using medicines in addition to them, find 

 some method of rendering the immediate efifects of the injection 

 permanent. 



For the purpose of relaxing the contraction of the pulmonary 

 capillaries, nitrite of amyl would seem, as Dr. Jones says, to be 

 the very remedy. In this Journal for October 14th (1871), Dr. 

 George Johnson observes that nitrite of amyl may not act on the 

 pulmonary capillaries as it does on the systemic ones. I have, 

 however, tried it on animals, and find that it does. When given 

 to rabbits, it causes the systemic capillaries to dilate enormously, 

 the blood flows rapidly into the veins, and the pressure on the 

 arterial system sinks in a corresponding degree. If it did not 

 produce dilatation of the pulmonary as well as of the systemic 

 capillaries, the blood which pours rapidly into the veins could 

 not pass with equal rapidity out of them through the pulmonary 

 vessels, and it would consequently accumulate in, and distend 

 the right side of the heart. In order to see whether this was 

 tlie case or not, I thoroughly narcotised a rabbit with chloral, 

 put a cannula into its trachea, and kept up artificial respiration. 

 I then opened the thorax, and, after carefully noting the appear- 

 ance of the heart, passed the vapour of nitrite of amyl, mixed 

 with air, into the lungs. When this was done, the cardiac pul- 

 sations became a little quicker, but not the slightest distension 

 of the right side of the heart or of the jugular vein could be 

 observed. I repeated the experiment several times with the 

 same result. There is no reason to suppose that the chloral 

 with which the animal was narcotised altered in any way the 



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