ISO 



POULTRY PRODUCTION 



tliis (lift'erence for hens and pullets of the same strain and 

 under identieal eonditions was 1.77 pounds i)er hundred 



prrtrQ 



Curtis' found tliat e.n'gs increase in wei.nlit e(.)ntinuously 

 up to the end of the second layinii: season, hut at a slower 

 and steadily decreasing rate. 



Development of the Chick. — The growth of the chick in 

 the egg occupies the incuhation period, which is analogous 

 to the gestation period in mammals. It begins with the 

 fertilization of the o\'imi aud continues until liatching or 

 birth, luiless checked b\' some unfavorable condition. 



Ill an iiK.'iiSat' 

 Slali.iii ) 



Development begins by sim])Ie cell division in the living- 

 portion of the egg, which is called the blastoderm, or, more 

 commonly, the germ spot. The first de^'elopment is a clear 

 area called the area pellucida, and surrounded by a denser 

 ring of cells called the area opaea. The growth of the embryo 

 takes place in the area pellucida. In this area the so-called 

 primiti\-e streak develops, whii'li is the first sign of the chick's 

 body. This j)oiiit in <le\ eloi^iuent is reached at about 



' Maine Bulletin No 22S. 



