On narcotism by the inhalation of vapours. Parts XVII and XVIII / by John Snow.

  • John Snow
Date:
1852
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Licence: Public Domain Mark

Credit: On narcotism by the inhalation of vapours. Parts XVII and XVIII / by John Snow. Source: Wellcome Collection.

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    EXPIfRIMENTS ON THE AUTIOV OF CHLOROFORM. out at the time of the injection, aud there was a quivering motion of tlie toes. These extremities, together with the posterior half of the trunk, hecame in- stantly affecited with post-mortem ri- gidity, and were totally insensible to tiie shocks of tiie electro-magnetic bat- tery. The anterior e.Ktremities, aud, indeed, all the anterior part of the body which had not b?en injected with ether, remained sensible to tlie shocks of the battery, and only became rigid between two and three hours after death. The heart ceased to act at the moment of the injection, some etiier having been dropped on it from the syringe. Exp. 82 —An ounce of rectified spirit of wine was injected into the aorta of a cat immediately after death from chlo- roform. There wei-e muscular contrac- tions at the moment of injection, but no contractions could be excited afterwards by mechanical irritation, although the muscles were very irritable just before, and were quivering when not touched. The heart, which was j^i'eviously beat- ing, also ceased to act. Post-mortem rigidity began to take place five minutes after the injection, and it still existed eight days afterwards. Exp. 83.—A cat was killed by inha- lation of chloroform, and three minutes after death three drachms of rectified spirit of wine, of 80 per cent., were mixed with three drachms of water, and in- jected into the descending aorta. The posterior extremities were stretched out at the moment of the injection, and almost immediately began to be rigid ; and in less than ten minutes after the injection, the whole of the posterior half of the body was veiy rigid, whilst the anterior parts were quite flexible. An hour after death rigidity was com- mencing in the anterior extremities, and in half an hour more they and the neck were quite rigid. This cat was killed on Dec. 1st, 1850, and was kept in a room with a fire. The rigidity of the anterior half of the body began to subside at the end of a week, but that of the posterior extremities not till a fortnight had elapsed; and they were still quite fresh, although putrefaction was commencing in the chest and neck. As absorption of vapour continues in the frog by its skin after the respiratory movements have ceased, it is not neces- sary to resort either to dissection or injection in them, as in manunalia, in order to cause the extinction ot irri- tability, and bring on the post-mortem rigidity. It can be induced in a very few minutes by exposure to the vajiour of ether or chloroform, although, under ordinary circumstances, the muscles re- miiin long irritable and flexible in these animals. In some interesting experi- ments lately detailed in the Medical Gazette by Mr. W. F. Barlow,* that gentleman produced rigidity in a single limb of living frogs without nruch affect- ing the rest of the animal; he also observed what I had previously re- marked,! that the setting in of rigidity in these animals is sometimes accom- panied by a movement of the body. The state which is called post-mortem rigidity appeal's to be the natural condi- tion of muscle when no kind of change in its composition is taking place. As long as the feeble oxidation continues, which enables it to be irritable after death, it remains flaccid; but when this ceases, from want of oxygen, from reduc- tion of temperature, from the counter affinity of a narcotic, or from exhaustion of the nutrient materials, the muscle becomes rigid, aud remains so till a new kind of oxidation—that of putrefaction —commences, when it again becomes flaccid. Although the muscles, when affected with this kind of rigidity, are in a state of completely suspended anima- tion, they are not always incapable of again living; for M. Brown Sequard has restored the irritability of the mus- cles of a dead guinea pig after they had been rigid from ten to twenty minutes, by making the blood of a living animal of the same species circulate in its vessels. Although reducing the tempe- rature hastens rigidity, it is not essential to it; for I have seen a fcetus at the full term born in a state of complete rigor mortis. In a former paper]; several proofs were given that chloroform and ether do not prevent oxidation in the system by themselves combining with the oxy- gen of the blood. Among these jn-oofs were some experiments showing that the chloroform and ether ai-e exhaled again unchanged from the blood as it circulates through the lungs. The paper of ne.xt week will contain an inquiry into the manner in wdiich these nar- cotics act in limiting and preventing oxidation in the living frame. * Page 713. t Med. Gaz., vol. xlii. p. 415.