Clifton College Scientific Society. 57 



of climate, which, under the same circumstances, will always pro- 

 duce the same, or nearly the same, results ? 



Possibly there is no part of the natural history of man more 

 interesting than that which describes the progressive advancement 

 and decay of human life from the cradle to the grave. Nothing 

 exhibits such a striking picture of our weakness as the condition 

 of an infant immediately after birth. Incapable of employing its 

 organs, it requires assistance of every kind. In the first moment 

 of existence it presents an image of pain and misery, and is 

 weaker and more helpless than the young of any other animal. 

 Tlie infant now respires, and begins to utter sounds and cries. 

 Most animals are blind for some days after their birth. Infants 

 behold light the moment they come into the world. A new-born 

 child cannot distinguish objects, because it is incapable of fixing 

 its eyes upon them. About the end of forty days the infant begins 

 to hear and smile. About the age of seven months children 

 begin to cut their teeth, and these do not come without pain. 

 The pulse in children is much quicker than in adults, and from 

 this it may certainly be inferred that the internal heat is in the 

 same proportion greater. Till three years of age the life of a 

 child is exceedingly precarious. In two or three years it becomes 

 more certain, and at seven years of age a child has a better chance 

 of living, it is said, than at any other period of life. The jDeriod 

 of infancy is followed by boyhood and adolescence. This commences 

 at the age of twelve or fourteen, and usiially ends about thirty. 

 The body having acquired its full height during the period of boy- 

 hood, and its full dimensions in adolescence, remains for some years 

 in the same state before it begins to decay. This is the period 

 of manhood, which extends over a space of about twenty years, 

 from the age of thirty or thirty-five to that of fifty or fifty-five. 

 Physiologists give the name of old age to that period of life which 

 commences immediately after the age of manhood and ends at 

 death ; and they distinguish gray old age from that of decrepi- 

 tude. But it has been thought better not to give such an exten- 

 sive signification to the word. Men are not old at the age of 

 fifty or fifty-five, and though the body may give signs of decay, 

 we can hardly admit that it has arrived at the period of old age. 

 Decline begins from forty to forty-five or sixty to sixty-five 

 years of age. At this time of life the diminution of fat is the 

 cause of those wrinkles which begin to appear in the face and in 

 other parts of the body. The skin not being supported by the 

 same quantity of fat, and being incapable of contracting for want 

 of elasticity, sinks down and forms folds. In the decline of life 

 a remarkable change takes place in vision. At sixty or sixty-five 

 years of age the signs of decline become more and more visible, 



