CADAVERIC RIGIDITY. 849 



female the development of the generative organs is attended with important 

 physical and moral changes. 



The different ages recognized by physiologists are the following : Infancy, 

 from birth to the age of five years ; adolescence, or youth, to the twenty-fifth 

 year ; adult age, to the thirty-fifth year ; middle life, to the fiftieth year ; old 

 age, to the sixtieth year ; and then, extreme old age. A man may be re- 

 garded at his maximum of intellectual and physical development at about the 

 age of thirty-five, and he begins to decline after the sixtieth year, although 

 this rule, as regards intellectual vigor, has many exceptions. 



As regards nutrition, it may be stated in general terms that the appro- 

 priation of new matter is a little superior to disassimilation, to about the 

 age of twenty-five years ; between twenty-five and forty-five these two pro- 

 cesses are nearly equal ; and at a later period the nutrition does not com- 

 pletely supply the physiological waste of the tissues, the proportion of organic 

 to inorganic matter gradually diminishes, and death follows, as an inevitable 

 consequence of life. In old age the muscular movements gradually become 

 feeble ; the bones contain an excess of inorganic matter ; the ligaments be- 

 come stiff ; the special senses generally are somewhat obtuse ; and there is a 

 diminished capacity for mental labor, with more or less loss of memory 

 and of intellectual vigor. It is a curious fact that remote events are more 

 clearly and easily recalled to the mind in old age than those of recent occur- 

 rence ; and, indeed, early impressions and prejudices then appear to be un- 

 usually strong. 



It frequently happens in old age that some organ essential to life gives 

 way, and that this is the immediate cause of death, or that an old person is 

 stricken down by some disease to which his age renders him peculiarly liable. 

 It is so infrequent to observe a perfectly physiological life, continuing 

 throughout the successive ages of man, that it is almost impossible to present 

 a picture of physiological death ; but it sometimes occurs that there is a 

 gradual fading away of vitality in old persons, who die without being affected 

 with any special disease. It is also difficult to fix the natural period of human 

 life. Some persons die, apparently of old age, at seventy, and it is rare that 

 life is preserved beyond one hundred years. The tissues usually die succes- 

 sively and not simultaneously, nearly all of them being dependent upon the 

 circulating, oxygen- carry ing blood, for the maintenance of their physiological 

 properties. It has been demonstrated, indeed, that the properties of tissues 

 may be restored for a time, after apparent death, by the injection of blood 

 into their vessels. 



After death there often is a discharge of the contents of the rectum and 

 bladder, and parturition, even, has been known to take place. The appear- 

 ance which indicates growth of the beard after death is probably due to 

 shrinking of the skin and, perhaps, contraction of the smooth muscular fibres 

 attached to the hair- follicles. The most important phenomenon, however, 

 which is observed before putrefaction begins, is a general rigidity of the mus- 

 cular system. 



Cadaveric Rigidity (Rigor Mortis). At a variable time after death, usu- 



