PRAIRIE FARMER'S POULTRY BOOK 



ment during the first three or four days of chick life. The 

 albumen is used as nourishment by the developing embryo. 

 The shell becomes soft and easily broken on account of the 

 action of the carbon dioxide. 



The most wonderful changes, however, take place in the 

 embryo. When the sperm cell fuses with the germ cell the 

 resulting embryo is but a single, primordial cell, but before 

 the egg leaves the oviduct the embryo has become two cells, 

 known as the blastoderm. At this point development is ar- 

 rested until favoring conditions occur outside the parent body. 

 Sometimes the egg is retained in the body for a considerable 

 period, incubation sets in, later the embryo dies, and the result 

 is what is known as a stale fresh-laid egg. 



The following are some of the changes that take place in 

 the embryo as it progresses toward the fully formed chick: — 



At the end of the first day growth is apparent and blood 

 vessels can be seen. 



At the end of the fifth day the eye and heart and lungs have 

 made their appearnce with radiating blood vessels. 



At the end of the 10th day the bones and muscles are quite 

 well developed. 



By the end of the ISth day the skin and feathers are 

 well developed. 



On the 18th day the first peep is heard, and on the 

 19th day the beak penetrates the enveloping membrane and 

 the process of hatching begins. 



How the Chick Hatches 



Before hatching takes place the embryo must be fully de- 

 veloped. To accomplish this requires a definite number of 

 heat units. When the proper temperature is maintained the 

 embryo receives the correct number of heat units in about 

 19 days, and I>atching then begins. If the temperature 

 is run too high, hatching begins before the 19th day. If run 

 at too low a temperature, the time of hatching is sometimes 

 prolonged to the 24th day. It is a good sign when the hatch 

 comes ofjf on time. 



Hatching begins by thrusting the beak through the mem 

 brane that encloses the chick into the air space at the large 

 end of the egg. The shell is then pipped. If pipping occurs 

 near the small end of the egg it shows an abnormal condition, 

 and the chick inay not be able to hatch. After the shell is 



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