RESPIRATION. 211 



luence in the production of the usual symptoms of asphyxia than the 

 icreased amount of carbonic acid. Indeed, the fatal effect of a gradual 

 emulation of the latter in the blood, if a due supply of oxygen be 

 luintuined, resembles rather that of a narcotic poison. 



In some experiments performed by a committee appointed by the 

 [edico-Chirurgical Society to investigate the subject of Suspended Ani- 

 latioti, it was found that, in the dog, during simple asphyxia, i.e., by 

 simple privation of air, as by plugging the trachea, the average duration 

 )f the respiratory movements after the animal had been deprived of air, 

 ras 4 minutes 5 seconds; the extremes being 3 minutes 30 seconds, and 

 minutes 40 seconds. The average duration of the heart's action, on the 

 )therliand, was 7 minutes 11 seconds; the extremes being 6 minutes 40 

 nets, and 7 minutes 45 seconds. It would seem, therefore, that on 

 an average, the heart's action continues for 3 minutes 15 seconds after the 

 minril has ceased to make respiratory eiforts. A very similar relation 

 was observed in the rabbit. Recovery never took place after the heart's 

 action had ceased. 



The results obtained by the committee on the subject of drowning 

 were very remarkable, especially in this respect, that whereas an animal 

 may recover, after simple deprivation of air for nearly four minutes, yet, 

 after submersion in water for 1| minute, recovery seems to be impossible. 

 This remarkable difference was found to be due, not to the mere submer- 

 sion, nor directly to the struggles of the animal, nor to depression of tem- 

 perature, but to the two facts, that in drowning, a free passage is allowed 

 to air out of the lungs, and a free entrance of water into them. It is 

 probably to the entrance of water into the lungs that the speedy death in 

 drowning is mainly due. The results of post-mortem examination strongly 

 support this view. On examining the lungs of animals deprived of air 

 by plugging the trachea, they were found simply congested; but in the 

 animals drowned, not only was the congestion much more intense, accom- 

 panied with ecchymosed points on the surface and in the substance of 

 the lung, but the air tubes were completely choked up with a sanious 

 foam, consisting of blood, water, and mucus, churned up with the air in 

 the lungs by the respiratory efforts of the animal. The lung-substance, 

 too, appeared to be saturated and sodden with water, which, stained 

 slightly with blood, poured out at any point where a section was made. 

 The lung thus sodden with water was heavy (though it floated), doughy, 

 pitted on pressure, and was incapable of collapsing. It is not difficult to 

 understand how, by such infraction of the tubes, air is debarred from 

 iva ehing the pulmonary cells; indeed the inability of the lungs to collapse 

 on opening the chest is a proof of the obstruction which the froth occu- 

 pying the air-tubes offers to the transit of air. 



We must carefully distinguish the asphyxiating effect of an insuffi- 

 cient supply of oxygen from the directly poisonous action of such a gas 

 as carbonic oxide, which is present to a considerable amount in common 

 coal-gas. The fatal effects often produced by this gas (as in accidents 

 from burning charcoal stoves in small, close rooms), are due to its enter- 

 ing into combination with the haemoglobin of the blood -corpuscles 

 (p. 95), and thus expelling the oxygen. 



