296 THE LIFE OF A BIRD. 



besides very numerous coatings of the white of 

 egg varnish, first on the shell itself, and then on 

 the several coats of paper, the whole forming a 

 covering so thick and horny that it must have 

 been actually impermeable. 



These eggs were put under a sitting hen and 

 were successively opened on the fourth, fifth, 

 sixth, seventh, eighth, ninth, and tenth days, and 

 the appearances were perfectly natural. The chicks 

 had gone through all their changes without the 

 smallest interruption ! At the twelfth day, when 

 the beautiful membrane with its blood-vessels the 

 so termed " beautiful substitute for the lungs" 

 is best developed, eggs thus densely covered were 

 opened, and the chick was found perfectly healthy, 

 and the membrane as exquisitely interlaced with 

 arteries and veins as usual. One of the covered 

 eggs was allowed to remain until the nineteenth 

 day, yet on opening, the chick was found perfectly 

 vigorous, and evinced strong disposition to escape 

 from its shell. 



A still more conclusive series of experiments 

 were then commenced. After proceeding with 

 the eggs as before, only super-adding an additional 

 layer, making altogether five thicknesses of stout 



