I LIFE AND DEATH 27 



have been thus briefly indicated constitute the greater 

 part of what are called the vital action'^ of the human 

 body, and so long as they are performed, the body is said 

 to possess life. The cessation of the performance of these 

 functions is what is ordinarily called death. 



But there are really several kinds of death, which may, 

 in the first place, be distinguished from one another under 

 the two heads of local and of general death. 



(i) Iiocal death is going on at every moment, and in 

 most, if not in all, parts of the living body. Individual 

 cells of the epidermis and of the epithelium are inces- 

 santly dying and being cast off, to be replaced by others 

 which are, as constantly, coming into separate existence. 

 The like is true of blood-corpuscles, and probably of many 

 other elements of the tissues. 



This form of local death is insensible to ourselves, and 

 is essential to the due maintenance of life. But, occa- 

 sionally, local death occurs on a larger .scale, as the re- 

 .sult of injury, or as the consequence of disease. A burn, 

 for example, may suddenly kill more or less of the skin ; 

 or part of the tissues of the skin may die, as in the case 

 of the slough which lies in the midst of a boil ; or a 

 whole limb may die, and exhibit the strange phenomena 

 of mortification. 



The local death of some tissues is followed hy their 

 regeneration. Not only all the forms of epidermis and 

 epithelium, but nerves, connective tissue, bone, and at 

 any rate, some muscles, may be thus reproduced, even on 

 a large scale, 



(ii) General death is of two kinds, death of the bo'iy as 

 a whole, and death of the tissues. By the former term is 

 implied the absolute cessation of the functions of the brain, 

 of the circulatory, and of the respiratory organs ; by the 

 latter, the entire disappearance of the vital actions of the 

 ultimate structural constituents of the body. When 

 death takes place, the body, as a whole, dies first, the 

 death of the tissues not occurring until after an interval, 

 which is sometimes considerable. 



