ON THE PHYSIOLOGICAL ACTION OF NITRITE OF AMYL. 127 



Pathological Effects of the Nitrite of Amtl. 



In cases where the nitrite of amyl is carried to its extrcmest effects, 

 the appearances of the internal organs present some modifications. The 

 appearances are not the same in every instance, hut vary according to the 

 mode in which the suhstance is administered. If it be administered very 

 quickly, the lungs and all the other organs are found blanched and free of 

 blood, the right side of the heart is engorged with blood, and the left side is 

 empty, the brain being free of congestion. If the substance be administered 

 slowly, the lungs are congested, the brain is congested, and blood is found 

 both on the right and left sides of the heart. The organs of the body are 

 also of a dirty reddish-brown colour, and the blood is similarly discoloured, 

 ]io distinction in colour existing between the arterial and venous bloods. 

 Notwithstanding the violent action of the heart, I have never seen rupture of 

 any vessel nor extravasation of blood. The inner lining of the blood-vessels 

 is unchanged, and the valvular mechanism of the heart maintains its integrity. 

 It is to be remembered that these observations have all been made on healthy 

 animals. 



COMFAEISON' OF EfFECTS OF THE NlTEITE WITH OTHER AlITL-COMPOirNDS 



AND OTHER BoDIES. 



Observations. — Series 10. I have compared the action of nitrite of amyl 

 with certain other of the amyl-compouuds, but I have not had sufficient time 

 to complete this line of research, each new compound opening up for itself a 

 new field of observation rich in varietj-. As yet I have only tried the com- 

 parison vtith amylene and acetate of amyl. Amylene differs fi-om the ni- 

 trite in that it acts as an anaesthetic ; but it resembles the nitrite in exciting 

 the circulation in a minor degree and in causing redness of the skin. The 

 symptoms produced by amylene are, however, very transitory as compared 

 with those following the use of nitrite ; there is this in common, that neither 

 of them entirely destroy consciousness, but amylene destroys sensibility, which 

 the nitrite does not. T once saw Dr. Snow give amylene to a boy who was 

 being subjected to an operation, and who was playing with a ball the whole 

 time. The acetate of amyl, in comparison with the nitrite, seems to me to 

 produce a more marked local and a less severe general effect. It causes on 

 inhalation, not only redness of the face, but swelling and soreness of the 

 mucous surfaces, without any violent excitation of the heart. Erom chloro- 

 form the nitrite differs in that it does not produce anaesthesia ; and the same 

 remark applies to ether, the monochlorm-etted chloride of ethyle, nitrous 

 oxide gas, Dutch hquid, turpentine, and ammonia, although it resembles all 

 these in that it excites the cii'culation in the early stages of its action. The 

 only substance which approaches the nitrite in action is woorah, a vegetable 

 compound which is much the same in its elementary composition. Woorali 

 produces less preliminary excitement of the circulation, it paralyzes more 

 determinately all the muscles except the heart, and being a solid substance, 

 possessing no means of escaping from the body except in solution, it is more 

 slowly eliminated. Woorali and the nitrite have, however, this in common, 

 they produce paralysis of the extreme filaments of nerves before they influence 

 the centi-al portions of the nervous circuit. 



Cause of the EAProiTY of the CiRctrLATioN under Nitrite of Ajitl. 

 Why the nitrite of amyl should produce such suddenly increased action of 

 the heart is a point of great physiological interest. I thought at first that 



