184 



POULTRY PRODUCTION 



Near the middle of tJje second (la>- a Ijlind sac Ijegiiis to 

 piisli out from the jjosterior end of the aUmentary tract, 

 wliicli grows rapidly until it completely covers the embryo 

 at ahout the ninth day and has come in close contact with 

 the shell membrane. It is aLundantly supplied with blood- 

 vessels and, although it is outside the body of the embryo, 

 serves as the organ of both respiration and excretion until 

 the chick commences to pip the shell and the lungs and 

 kidneys of the chick commence to function. 



It is the veins of this allantois which are seen radiating 

 horn the embryo at the first testing, about the seventh day 



Fig. 89 



irauce 

 ((_'oiii 



a chick emijryo after thirty-six l;iours in : 

 sy of Kansas Agiicultural IO\|)ri inicnt St; 



I'lllialur, 



(jf incubation, and wdiicli may be noted plainly at the second 

 testing, about the fourteenth day. As soon as the chick 

 pips the shell, pulmonary circulation starts and the allantois 

 ceases to function, begins to degenerate, and is left behind 

 in the shell at hatching. 



Up to the sixth or seventh day there is nothing aliout the 

 chick emljryo that would help one to distinguish it from the 

 embryo of any other animal. At this time the legs and wings 

 l)cgin to take a recognizable form. The body, which has 

 been very small in proportion to the head, begins to develop 



