^X'^' DEATH. 435 



The individual life has been destroyed by a mechanical force : the 

 potential energy of the organism provides food for luckier organisms, 

 and sooner or later passes from the world as heat. But in the 

 large organism, as in the small, what has taken place is mechanical 

 interruption of a complicated process, resulting ultimately in chemical 

 death — the running off of the potential energy. 



The leading idea in this paper is to find in the various 

 phenomena grouped under the term death, never the opposition of a 

 kindred mysterious force to the mysterious vitalism, but the action 

 of known mechanical or chemical agencies, and to suggest the 

 inference that the life of the organism or of the cell, coming to an 

 end as it does by known agencies, cannot itself depend in essence on 

 any transcendental force; that, in fact, as the negative conditions 

 of life are purely chemical and physical, life itself, however com- 

 plicated, must be a congeries of phenomena ultimately to be resolved 

 into purely chemical and physical forces. 



When we consider the higher animals we find that death is 

 always more or less violent. As Michael Foster says, " The central 

 factor of life is the circulation of the blood, and the blood is not only 

 useless but injurious unless it be duly oxygenated, and in the higher 

 animals the oxygenation of the blood can be duly effected by means 

 of the respiratory muscular mechanism presided over by the respira- 

 tory centre in the bulb. Thus, the life of a complex animal is, when 

 reduced to a simple form, composed of three factors — the maintenance 

 of the circulation, the access of air to the haemoglobin of the blood 

 and the functional activity of the respiratory centre, and death may 

 come from the arrest of any one of these three. As it has been put, 

 death may begin at the heart, or the lungs, or the brain." 



It requires little medical knowledge to refer the final symptoms 

 of any fatal disease to one of these — the three gates of death of 

 the older writers. Turning over a few of them, one finds the proxi- 

 mate causes of death to group themselves simply. 



Death through the heart may come by inhibition, as when a 

 blow on the abdomen or iced milk on the stomach stimulates the 

 peripheral ends of the vagus. Or it may come by cardiac failure as 

 in fatty degeneration, or in valvular diseases. 



Death through the lungs may come as asphyxia from lung 

 diseases, from capillary bronchitis, or from pneumonia. Or asphyxia 

 may result from anaemia caused by loss of blood from haemorrhage 

 or want of haemoglobin. Or the respiratory nerves may be paralysed, 

 as in diphtheria or bulbar paralysis. 



And, lastly, death through the brain may come in a multitude 

 of ways. Centres may be suddenly destroyed by wounds, or by the 

 culmination of tumours, or they may be paralysed by high tempera- 

 ture, or by a multitude of organic poisons arising from organic 

 diseases, like Bright's, or produced by parasitic bacteria. 



Even in death from old age we find the dark mother throwing 



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