INCUBATION. 



On the first thoughts upon this subject it may appear 

 of little importance to the general observer how long it 

 may require to hatch an egg, and under what conditions 

 it can be hatched, but after a little consideration many 

 circumstances will become known that cannot fail to 

 impress upon us the powerful and undeviating law that 

 exists in all created life, the fixed period for change from 

 one state of existence to another, not only observable in 

 the advancement of the embryo in the egg, but continuing 

 through the whole life of every individual of every species. 

 As the most ready and easily-explained examples, let us 

 take the eggs of birds: we find an unalterable and 

 measured time required for hatching the eggs of one 

 class or order of birds, and in this way we find that the 

 eggs of some kinds of birds will hatch at a much earlier 

 period than others ; as, for instance, the pigeon's eggs 

 hatch at the end of fourteen days, the common fowl at 

 twenty-one days, the duck at twenty-eight days, the 

 geese at thirty-five. It will be seen by this the remark- 

 able regularity of the period of the multiplying of the 

 universal seventh day. The longest period required for 

 hatching the eggs of birds occurs with the struthious birds 

 (ostriches), and the period is seven times seven, or seven 

 weeks. It will be thus seen that the earliest time 

 recorded will be twice seven and the longest time known 

 seven times seven. This certainty of time, as before 



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