RESPIRATION. 207 



rapidly lost. The diminution of oxygen has a more direct influence in 

 the production of the usual symptoms of asphyxia than the increased 

 amount of carbonic acid. Indeed, the fatal effect of a gradul accumu- 

 lation of the latter in the blood, if a due supply of ox \ gen is maintained, 

 resembles rather that of a narcotic poison, and not of asphyxia. 



In some experiments performed by a committee appointed by the 

 Medico-Chirurgical Society to investigate the subject of Suspended Ani- 

 mation, 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 

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

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

 and 4 minutes 40 seconds. The average duration of the heart's action, 

 on the other hand, was 7 minutes 11 seconds ; the extremes being 6 

 minutes 40 seconds, and 7 minutes 45 seconds. It would seem, there- 

 fore, that on an average, the heart's action continues for 3 minutes 15 

 seconds after the animal had ceased to make respiratory efforts. A very 

 similar relation was observed in the rabbit. Kecovery never took place 

 after the heart's action had ceased. 



The results obtained by the committee on the subject of droivning 

 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-j- minutes, recovery seems to be impos- 

 sible. This remarkable difference was found to be due, not to the mere 

 submersion, nor directly to the struggles of the animal, nor to depres- 

 sion of temperature, but to the two facts, that in drowning, a free pas- 

 sage 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 examination 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 con- 

 gestion much more intense, accompanied with ecchymosed points on the 

 surface and in the substance of the lung, but the air tubes were com- 

 pletely 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 infarction 

 of the tubes, air is debarred from reaching the pulmonary cells ; indeed 

 the inability of the lungs to collapse on opening the chest is a proof of 

 the obstruction which the froth occupying 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 gases 

 as carbonic oxide, which is contained to a considerable amount in com- 

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

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

 entering into combination with the haemoglobin of the blood-corpuscles 

 (p. 87). and thus expelling the oxven. 



