33G PHYSIOLOGY. 



description is as applicable now, as it was four thousand 

 years ago. 



20. Those who die from old age are few ; being, in the 

 city of New York, but one in thirty-four. In New En- 

 gland, generally, the proportion is rather greater. The 

 mean duration of life in New York is but twenty.five years j 

 while the average rate of mortality, According to population, 

 is one in thirty-five) The diseases to which man is subject, 

 from the earliest fb the latest period of his existence, are 

 numerous, and many of them of a fatal character. Syden- 

 ham estimates that two thirds of mankind die of acute dis- 

 eases ; and that of the remaining, one third, or two ninths 

 of the whole, die of consumption, leaving only one ninth to 

 perish from other chronic maladies, and from pure old age. 



20. As age approaches, the functions are all performed 

 with less energy. The teeth fall out, and their sockets are 

 absorbed ; respiration is not as readily accomplished ; the 

 valves of the heart, and the coats of many of the arteries 

 become changed into bone, thus obstructing the circulation, 

 and often causing an intermittent pulse j nutrition Ian- 

 guishes ; the senses are blunted ; animal heat diminishes, so 

 that warmer clothing is demanded ; the muscular system 

 loses its power, and the body bends forward ; the limbs totter, 

 the mental as well as corporeal faculties often fail ; and the 

 individual is reduced to second childhood, so well described 

 by Shakspeare. 



" Last scene of all, 



That ends this strange, eventful history, 

 Is second childishness, and mere oblivion ; 

 Sans teeth, Sans eyes, Sans taste, Sans everything." 



As the other functions cease their office, sensibility gradual- 

 ly becomes extinct, and life almost imperceptibly takes its 

 flight. 



