REPRODUCTION 



117 



established in close relation to the inner surface of the shell of the egg of a 

 reptile or bird, providing for exchange of respiratory gases between the 

 blood and the external medium. As development proceeds the albumen 





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■r 13 ^ 

 O c8 ^ 

 m 0) ^ 



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becomes much reduced in bulk. The expanding allantois apparently 

 pushes the remainder of it out of most of the peripheral territory within 

 the egg shell and causes it to become concentrated at one spot (Figs. 86 



