122 Practical Zoology. 



the shell is last formed, and is absent in the case of most animals. 

 In the development of birds all their nourishment, before hatching, 

 must be stored in the egg ; hence its large size. 



9. Set a hen on a dozen eggs ; mark the date ; open and 

 examine an egg each day; if the egg was fertilized, the cells 

 of the germ spot multiply by division, and soon take definite 

 arrangement ; at the end of twenty-four hours the backbone is 

 outlined ; during the second day the brain begins to develop, and 

 'the heart appears ; on the fourth day the legs and wings make 

 their appearance as flattened buds ; during the first few days it is 

 hard to say whether the embryo was that of a bird, a reptile, or a 

 mammal ; after this, the characters peculiar to birds become evi- 

 dent, the feathers begin to develop, and, later, the particular kind 

 of bird may be recognized. 



Egg-laying animals are called oviparous. If the young develop 

 within the body of the parent, receiving nourishment from the 

 blood of the parent, the animal is said to be viviparous; "or, 

 the young may complete its development while the egg remains 

 in the interior of the body of the parent, but quite free and un- 

 connected with it, as in those vertebrates which are termed ovo- 

 viviparous." 



The study of development is called embryology. 



Topics for Reports. Ostrich Farming. Origin of our Domestic 

 Fowls. Origin of the Domestic Pigeon. Varieties of Pigeons. 

 Game Birds. The Guinea Fowl. The Turkey. Hawking. Carrion- 

 eating Birds. Birds whose Plumage is used for Ornament. Birds 

 and Millinery. Laws for Bird Protection. History of the English 

 Sparrow. The " American " Eagle. The Fishhawk. The Whip- 

 poor-will. Introduction of New Game Birds. The Road Runner. 

 The Mocking Bird. The Water Ouzel. Hawks and Owls. 



Read American Natural History, Hornaday. 



