278 report— 1865. 



when brought into contact with dead organic material, it is much less activo 

 in this respect than any of the compounds which have up to this time been 

 before us. 



The physiological action of the iodide of amyl is well illustrated when 

 the substance is administered with the atomizer, but it may be admi- 

 nistered by direct inhalation. The symptoms induced are peculiar, being a 

 mixture of those brought out by the nitrite of amyl, the hydrated oxide and 

 the acetate. In the first stage of inhalation there is a profuse flow of 

 tears and increase of saliva, followed by rapid breathing and vehement action 

 of the heart. In the second stage there is prostration of the muscular 

 system with commencing rigors ; in the third stage there is entire prostra- 

 tion, and precisely as with the oxide and acetate, there are regular series 

 of general tremulous movements which can be excited at any moment by 

 touching or by a sharp noise. During the tremor the limbs are agitated in 

 movements which are so rapid that they cannot be counted. Pushed to 

 a fourth degree, the breathing becomes paralysed, and the action of the heart 

 intermittent and at last prolonged. But at this last degree, when extinction 

 of life is within a second, there is no insensibility to pain. The merest prick 

 causes expression of consciousness. Removed from the vapour, even when 

 the existence of life is almost doubtful, recovery, if there be the faintest de- 

 tectable action of the heart, is certain, and not only so, but it is rapid also. 

 In the course of recovery the tremors quickly subside, but a special and 

 curious phenomenon is commonly presented, consisting of a series of revolu- 

 tions of the body in a circle. At first the animal moves round almost on its 

 own axis ; as it regains power, it makes a little circuit, and then a wider 

 one ; at length it moves less methodically in jerks, and last of all attains the 

 straight line. It seems at no time to suffer anything, and yet always to be 

 alive to what is passing. It eats food voraciously on recovery. I shordd 

 add that during the whole process there is copious elimination of water from 

 the lungs, skin, and indeed all the cniunctory organs. 



If the blood be examined microscopically before, during, and after the in- 

 halation, several changes are observed. The colour of the blood is not 

 darkened, but tbe fibrine appears to imdergo entire solution, while the blood- 

 corpuscles in greater part retain their natural characteristic form. The 

 dissolved condition of the fibrine lasts many hours, and if the skin be pricked 

 the blood flows for an unusual time, but it is bright red in colour. When 

 added to drawn blood, the iodide renders the coagulation loose and feeble, but 

 does not stop the process altogether, possibly because its molecules do not 

 come into such minute contact with the blood as when they are brought into 

 union with the blood in the lungs. The upper surface of blood charged 

 with the iodide becomes oxidized quickly in the air, and exhibits a bright 

 red layer very deep and regular. ' 



The iodide causes little irritability of skin or of mucous membrane. It is 

 not disagreeable to inhale, but it excites secretion of saliva. It also produces 

 vascular redness of the extremities during its inhalation. 



In regard to the whole of the amyl-compounds, the properties of which 

 I have investigated, I may state that, while they destroy the voluntary power 

 of the muscles, they seem in no way to destroy the muscular irritability, the 

 vis insita of Haller. This is proved by the facts that when the animal lies 

 most prostrate any muscle or any group of muscles can be called into brisk 

 action by the application of the galvanic stimulus, and that when an animal 

 is actually destroyed by them, the muscular irritability remains for many 

 hoiu-s after death. When the nitrite is employed as the destructive agent, 



