DEATH. 863 



CHAPTER VII. 

 DEATH. 



821. WHEN the animal kingdom is surveyed from a broad stand- 

 point, it becomes obvious that the ovum, or its correlative the spermatozoon, 

 is the goal of an individual existence; that life is a cycle beginning in an 

 ovum and coming round to an ovum again. The greater part of the actions 

 which, looking from a near point of view at the higher animals alone, we 

 are apt to consider as eminently the purposes for which animals come into 

 existence, when viewed from the distant outlook whence the whole living 

 world is surveyed, fade away into the likeness of the mere byplay of ovum- 

 bearing organisms. The animal body is in reality a vehicle for ova ; and 

 after the life of the parent has become potentially renewed in the offspring, 

 the body remains -as a cast-off envelope whose future is but to die. 



Were the animal frame not the complicated machine we have seen it to 

 be, death might come as a simple and gradual dissolution, the "sans every- 

 thing " being the last stage of the successive loss of fundamental powers. 

 As it is, however, death is always more or less violent ; the machine comes 

 to an end by reason of the disorder caused by the breaking down of one of 

 its parts. Life ceases not because the molecular powers of the whole body 

 slacken and are lost, but because a weakness in one or other part of the 

 machinery throws its whole working out of gear. 



822. We have seen that the central factor of life is the circulation of 

 the blood, but we have also seen that blood is not only useless, but injurious, 

 unless it is duly oxygenated ; and we have further seen that in the higher 

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

 of the respiratory muscular mechanism, presided over by the medulla oblon- 

 gata. 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 respi- 

 ratory centre ; and death may come from the arrest of either of these. As 

 Bichat put it, death takes place by the heart, or by the lungs, or by the brain. 

 In reality, however, when we push the analysis further, the central fact of 

 death is the stoppage of the heart, and the consequent arrest of the circula- 

 tion ; the tissues then all die, because they lose their internal medium. The 

 failure of the heart may arise in itself, on account of some failure in its 

 nervous or muscular elements, or by reason of some mischief affecting its 

 mechanical working. Or its stoppage may be due to some fault in its inter- 

 nal medium, such for instance as a want of oxygenation of the blood, which 

 in turn may be caused by either a change in the blood itself, as in carbonic- 

 oxide poisoning, or by a failure in the mechanical conditions of respiration, 

 or by a cessation of the action of the respiratory centre. The failure of 

 this centre, and indeed that of the heart itself, may be caused by nervous 

 influences proceeding from the brain, or brought into operation by means of 

 the central nervous system ; it may, on the other hand, be due to an imper- 

 fect state of blood, and this in turn may arise from the imperfect or perverse 

 action of various secretory or other tissues. The modes of death are in 

 reality as numerous as are the possible modifications of the various factors 

 of life ; but they all end in a stoppage of the circulation, and the with- 

 drawal from the tissues of their internal medium. Hence we come to con- 

 sider the death of the body as marked by the cessation of the heart's beat, 

 a cessation from which no recovery is possible ; and by this we are enabled 



