Human Physiology. 325 



been tainted by human impurities? Birds in cages may pine 

 and die ; crowded together they may be swept off by an epi- 

 demic; but how seldom do we find any disease among the free 

 birds of our forests. "Hearty and rugged as a bear," we say. 

 Does the fox have the measles? Do wolves die of scarlet 

 fever ? Has any one seen a leopard laid up with rheumatism ? 

 or a tiger down with typhus? or a gouty gorilla? Animals may 

 perish of hunger or by violence; but in natural conditions they 

 do not suffer from diseases. It is only our domestic animals 

 which are liable to disease, because we -deprive them of some 

 of the conditions of health, or expose them to the same or 

 similar conditions which produce our own diseases. 



When we consider how closely we resemble the higher 

 animals in our bodily constitution ; how similar are our bones, 

 muscles, nutritive and excreting organs, blood-vessels, nerves 

 and senses, we must see that health is as natural a condition to 

 us as to them. If an animal lives the life for which it is consti- 

 tuted to which its organisation is adapted it cannot have 

 disease. Its only natural death is one of gradual decay in old 

 age. And such is the only natural death of man. There is no 

 reason why he should not be as healthy as any plant, or fish, or 

 bird, or animal ; and it is probable that man is, by the nature 

 of his organisation, the most healthful and longest lived of all 

 the animal creation. 



In the Zoological Gardens some effort is made to place 

 every bird and animal in its natural and therefore healthy 

 conditions ; but we see how imperfectly it is done. Birds that 

 in a state of nature would fly fifty or a hundred miles every 

 day, using all their energies to gather their food, are shut up in 

 cages and fed. The eagle and condor, sea gulls and Mother 

 Carey's chickens, born to range the mountain peaks and the 

 wide ocean, must pine in such an indolent captivity. A sick 

 monkey may be seen in a menagerie, but never, I believe, in 

 its native forest haunts, where it can spring from tree to tree 



