A Story Outline of Evolution 



come the necessity of grinding teeth, they developed their 

 stomachs into muscular gizzards and among the grain and 

 seed eaters, these gizzards are aided in their cutting and 

 grinding by sand and pebbles. They have thus developed a 

 mill within themselves Instead of reverting to their ancestral 

 teeth. In those species using food that requires the greatest 

 amount of stomach work before It can be digested, their 

 esophagus is dilated Into a crop In which the food Is softened 

 before passing on to the gizzard for grinding. 



The waders present an Interesting study. They are aqua- 

 tic in their habits but Instead of swimming and diving for 

 their food, they seek and obtain their food by wading along 

 the shores of the creeks, rivers, ponds, lakes and oceans. 

 Because of this habit, they are commonly called "shore birds" 

 or "waders." Nature has adapted them for such an exist- 

 ence by giving to them long legs, long necks and bills that are 

 longer than their heads. The night herons that belong to 

 this class are uncanny In their methods of fishing. They 

 stand In the reeds along the shallow shores sometimes for 

 hours waiting for their prey. The smaller fish are picked up 

 and swallowed whole while the larger ones, some weighing 

 as much as four pounds, are pierced to the vertebra by the 

 sharp bill and paralyzed, and then cut into pieces small 

 enough to be swallowed. 



No place in the entire scheme of life are the social rela- 

 tions of plants and animals to one another more clearly dem- 

 onstrated than in the part played in the ecology of Nature 

 by the birds. Each of the many species of birds are playing 

 their part In the Plan of Creation. The vultures and scaven- 

 gers are ridding the earth of its putrefying dead. The song- 

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