This is the unfortunate termination of many diseases, but the tendency to death is frequently more an accidental circumstance than a necessary part of the phenomena of the disease.

Life may persist along with the abolition of most of the functions of the body. If the respiration and circulation persist, the remaining functions, even those of the brain, may be in abeyance and yet the person may survive. If we look at the actual process of dying we shall find that in most cases the heart or the respiratory movements first give way, although in some instances it may be difficult • to determine which has first ceased. According to Bichat there are three modes of death, namely, by the brain, by the lungs, and by the heart, but from what has been noted above it is clear that these may be included in the two mentioned.

Death by the lungs is due to failure in the respiratory movements. This may occur suddenly by paralysis of the respiratory centre in the medulla oblongata, as in haemorrhages in the brain, but for the most part it occurs gradually from exhaustion of the respiratory centre, and is then called death by Asphyxia. Such exhaustion will ensue when, from obstruction of the air passages or vitiation of the air, the respiration has been for a time carried on with great difficulty.

Death by failure of the heart's action is a more frequent mode of death. It may be the result of irritation of the vagus centre in the medulla oblongata from injury to the brain, though in this case the failure of the heart may be simultaneous with cessation of respiration. This form of paralysis of the heart, however, is1 of rare occurrence. Again, a sudden reflex paralysis of the heart from shock may occur. There may also be death from failure of the heart due to disease in the organ itself, and here also the death is very often sudden. A frequent cause of sudden death, for instance, is obstruction of a branch of the coronary artery. This may lead to such derangement of the nutrition of the heart's muscle as to cause paralysis and cessation of its contractions.

But cessation of the heart's action is often the mode of death when the seat of disease is distant from that organ or its nervous apparatus. In that case the heart is affected secondarily. It is weakened, it may be, by the condition of the blood being altered, so that the requisite amount of nutriment is no longer afforded to the heart; or it may be injured by the blood being increased in temperature or contaminated by abnormal products. In these cases the heart partakes in the general weakening of the body and gradually ceases to contract.

Failure of the heart has an immediate effect on the circulation in the lungs, and we shall see afterwards that (edema of the lungs, which is characterized by exudation of fluid into the lung alveoli, is one of the most constant effects of this condition. The laboured breathing and rattle in the throat, which are so frequent in the last stages of disease, are the usual signs of oedema of the lungs, so that although these signs call attention to the respiratory organs, the real primary failure may be in the heart.

It will be seen that the proclivity to death in the various forms of disease will depend on the degree to which the disease affects the respiration or the heart's action, but more particularly the latter. In this. view of it the actual question of death or survival will frequently depend on the staying power of the heart. The ability of the heart to continue its contractions during the most severe period of an illness will frequently determine whether the person is to die or recover. This is an important point to keep in mind in actual practice. There are great differences in the staying power of the heart in different persons, and so there are great differences in the fatality of the same diseases. The ability of the heart, like other local conditions, is largely determined by inheritance. It is probably one of the main factors in determining the duration of life, and longevity depends probably more on the character of the heart than on any other single circumstance.

Literature

John Hunter, Lect. on Principles of Surgery, in vol. i. of Works edited by Palmer, 1835; Uhle und Wagner, Allg. Path., 5th ed. 1872. Inheritance and Constitution. - Coats, in Lancet, Jan. 7, 14, and 21, 1888, Brit. Med. Jour., 1889,'ii., 409; Galton, Inquiries into Human Faculty, 1883; Kleinwachter, Die Lehre von d. Zwillingen; Sedgwick, Med. Chir. Review, 1861 and 1863; Wickham Legg, St. Barth. Hosp. Rep., 1881; Finlayson, Glasg. Med. Jour., July, 1882, and Jan., 1881; Gee, St. Barth. Hosp. Rep., 1877; Weil, Virchow's Arch., vol. xcv., 1884, p. 70; Koch, Traumatic Infective Diseases, Syd. Soc. 1880; Chauvead, Comptes Rendus, 1880; Pasteur, Sur la cholera des poules, Comptes Rendus, 1880; Darwin, Descent of Man, 2nd ed., 1874, p. 169; Spencer, Principles of Biology, 1864-7; Darwin, Variation of Plants and Animals, 1863; Francis Galton, Journ. of Anthropological Institute, 1875; Weismann, Germ-plasm, 1893. Age and Sex. - See especially Quetelet, various works on physical conditions and causes of death, with statistics; Humphrey, Reports and Articles on Diseases of Old Persons, in Brit. Med. Jour., Dec. 11, 1886 (Table of Centenarians), March 5, July 30, 1887, March 10, 1888; Russell, Proceedings, Phil. Soc. Glasg., xix., 1888; Charcot, Clin. Lect. on Senile and Chronic Diseases, Syd. Soc. transl., 1881. Causes of Death. - Bichat - Rech. phys. sur la vie et la mort., in Encyl. des Sc. Med., 1835; Hilton Fagge, Practice of Medicine, 1886, vol. i., 7.