370 NITEITE OF AMYL IN THE COLLAPSE OF CHOLERA. 



action of the nitrite of amyl on the pulmonary vessels, for I 

 have found that other vapours, as well as certain poisons, 

 injected into the jugular vein, cause accumulation of blood in 

 the right side of the heart after the animal has been completely 

 narcotised. I have also observed that this accumulation of 

 blood, which I believe to be due to contraction of the pulmo- 

 nary vessels caused by the poison or vapour, has disappeared in 

 the case of one poison at least,* after the injection of another 

 drug which had been previously found to be an antidote to it 

 in other respects. With the prosecution of these experiments 

 I am at present engaged ; and I take this opportunity of thank- 

 ing Dr. Burdon Sanderson for his kindness in allowing me the 

 use of his laboratory and apparatus. 



Dr. Johnson also says that, even if nitrite of amyl were 

 shown to possess the power of relaxing the pulmonary capil- 

 laries in health, it might not do so in disease, or at any rate not 

 to the same extent. Some observations which I have made on 

 its action in angina pectoris lend probability to this idea, in 

 the paper already referred to, which I published in 1867, I 

 mentioned my belief that angina was due to spasmodic contrac- 

 tion of the capillaries ; and in a paper in the Clinical Society s 

 Transactions for 1870, I gave copies of one or two of the 

 sphygmographic tracings which led me to form this belief. In 

 it I noticed that occasionally after the anginal pain had dis- 

 appeared from every other part of the cardiac region, it remained 

 persistently at a spot two inches inside the right nipple. This 

 local persistence of the pain was accompanied by a peculiar 

 condition of the pulse, which seemed to me to indicate that the 

 pulmonary capillaries had not become relaxed to the same 

 extent as the systemic ones. As sphygmographic tracings, 

 especially when taken with an instrument like the one I used, 

 in which the pressure exerted by the spring could not be esti- 

 mated, sometimes admit of different interpretations, I append 

 copies of' some of them. I may mention, however, that these 

 tracings are strictly comparable with each other, although they 



* Muscarin, tlie active principle of amanita rauscaria, discovered by Professor 

 Sclimiedeberg, seems to produce contraction of tlie pulmonary capillaries, and 

 this is at once removed by atropia. 



