ON THE PHYSIOLOGICAL ACTION OF NITRITE OF AMYL. 125 



move. The animal, whenever he had the power, winced on being touched, 

 and showed signs of consciousnes.s. 



In an experiment performed by Dr. Gibb and myself, a cat ■was rapidly 

 struck down by being placed in a thousand cubic inch jar through which the 

 vapour from one fluid-drachm of the nitrite had been diffused from a surface 

 of bibulous paper. Death took place in two minutes. The animal was re- 

 moved and was watched with great care, but the breathing had ceased. The 

 pupils were dilated to their fullest extent. After a time we laid open the 

 chest. On exposure to the air, the heart was found contracting most vigo- 

 rously, and soon the muscles of respiration also commenced spontaneously to 

 contract, moving the ribs, and disturbing the abdominal viscera. The dia- 

 phragm contracted very steadily, and a muscle of the thigh, on being laid 

 bare, did the same. These contractions actually continued spontaneously 

 from twenty-four minutes past twelve until forty-eight minutes past one in 

 the day — a phenomenon which has I believe never before been observed after 

 death in any of the muscles of warm-blooded animals except the heart. 



Eespecting the heart itself, in this case it continued contracting on the 

 right side when all the other muscles were at rest. To observe the local 

 action of the nitrite on the heart, we gradually instilled three minims of it on 

 the right auricle. The muscular structure soon became of a dirty white, but 

 the contractions continued. At seven in the evening the amicle, with a seg- 

 ment of the ventricle, was still contracting five times in the minute ; at ten 

 o'clock it was contracting in the same way, although the lower limbs of the 

 animal were rigid from rigor mortis ; at twelve (midnight) it was contracting 

 at the rate of two per minute ; at one it was reported by Dr. Henry as con- 

 tracting strongly from one to two beats per minute ; at five a.m. I found it 

 myself contracting three times in a minute and a half, and at eight it made a 

 contraction on being touched with a needle. Eor many hours before this all 

 the other muscles of the body were rigid. Thus there was witnessed the 

 strange phenomenon of muscular contractility in the heart while all the other 

 muscles were rigid ; and of muscular contractility of the heart for nearly 

 eighteen hours after what would technically be considered the death of the 

 animal. 



Observations. — Series 7. If instead of administering the nitrite of amyl 

 through the skin, by the mouth, or by the lungs, it be injected under the skin 

 with a hollow needle, it exerts its influence in the same way, and leads, 

 though more slowly, to the same symptoms. From an injection of twenty 

 minims decided symptoms are induced in such animals as rabbits, cats, and 

 dogs, but after a time they recover. In the case of a yonng cat. Dr. Gibb 

 and I slowly instilled twenty minims of the nitrite under the skin, and when 

 the first symptoms had subsided we instilled twenty more. The result was 

 that the animal feU into a powerless condition, but continued to breathe. 

 Four hours after the last instillation it was the same, and was breathing six 

 times in the minute. Eight hoirrs afterwards, the upper and lower limbs 

 and the muscles of the neck being rigid, it was breathing once in two minutes, 

 and the respiratory motion did not absolutely cease for two hours later. 



Observations. — Series 8. Local effects of the nitrite. I have made some 

 very minute observations on the effect of the nitrite upon the capillary vessels 

 of the web of the frog's foot. The results are very uniform and decisive. A 

 few seconds after the web is treated with the nitrite, the capillary vessels arc 

 seen to dilate to more than twice their natural calibre, and the rate of motion 

 of blood is immensely quickened. After an interval of fifty or sixty seconds, 

 the vessels become tortuous as from irregular contraction of their walls ; then 



