EVOLUTION OF THE CHICK. 161 



The Embryo Chick opened to show the absorption of the yolk into the 

 body. 



yolk, evidently for the purpose of absorbing it and 

 conveying it to the veins, where it is assimilated to 

 the blood and applied to the nutrition of the chick. 

 Blumenbach persuaded himself of the actual passage 

 of the yolk from the floating vessels of the inner 

 surface of the bag into the blood-vessels which go to 

 the chicken; at least, he could distinguish yellow 

 streaks in the red blood contained in the veins*. 



On the nineteenth day the embryo can utter 

 sounds, and may be heard doing so through the shell. 



* Zool. Journal, ii. 433. 



P3 



