12 A FEW FACTS ABOUT ZOOLOGY. 



tempted, on casual examination, to refuse it a place among 

 the backboned animals. Look at the illustration, Fig. 7, 

 and you will clearly see the plan of backbone, notwithstand- 

 ing the change it has undergone. 



In birds we meet warm-blooded and air-breathing verte- 

 brates, egg-laying like the reptiles, amphibians, and fishes, but 

 their eggs are comparatively few in number, and their young 

 are hatched by the mother and fed by the parent birds till 

 they can provide for themselves. 



We find some of the fishes showing care for their off- 

 spring; a greater care than is shown in most fishes exhibited 

 by reptiles; a still greater brooding tenderness by the birds. 

 At last we rise to the mammalia, a class that is warm- 

 blooded, that breathes through lungs, that bring forth their 

 young alive and nurse them with milk. This group, the 

 mammalia, is the highest group of vertebrates, at the very 

 head of which stands man, looking heavenward, it is true, 

 but nevertheless rooted deeply in the animal kingdom. Even 

 in the lowest members of the mammalia we have the dawn- 

 ing of those family relations, those intimate ties between 

 parents and children, on which the whole social organization 

 of the human race is placed. Man is the crowning work of 

 God on earth ; but, though so nobly endowed, we must not 

 forget that we are the lofty children of a race whose lowest 

 forms lie prostrate within the water, having no higher aspi- 

 ration than the desire for food. We cannot understand the 

 possible degradation and moral wretchedness of man without 

 knowing that his physical nature is rooted in all the charac- 

 teristics that belong to his type, and link him even with the 

 fish. The moral and intellectual gifts that distinguish him 

 from them are his to use or to abuse ; he may, if he will, take 

 thought only for his lower nature, and be a mere backboned 

 animal, or he may rise to a spiritual height that will make 

 that which is his especial distinction the controlling element 

 of his being. 



