POULTRY LABORATORY GUIDE 43 



Iain-lined, using great care not to rupture the 

 yolk. Examine with the naked eye, and note 

 any great differences or marked stages in their 

 development. A hand lens will aid in more 

 clearly distinguishing and understanding many 

 of the stages of development. 



The growth of the embryo up to the seventh 

 day is briefly outUned as follows : During the 

 first twenty-four hours" the embryo develops 

 those parts which afterwards become some of the 

 leading organs of the body, namely : the head, 

 the vitelline vein, neural fold and groove. Note 

 the clear area about the embryo, called the area 

 pellucida. Note the presence of a peculiar mem- 

 brane which envelops the embryo, forming a 

 cavity in which it lies. It is made in folds, and 

 when these folds meet and coalesce above the 

 embryo, they unite so that the inner folds form 

 a continuous inner membrane or sack and the 

 outer membrane forms an outer membrane or 

 sack. The inner membrane forms a complete 

 closed sack around the embryo, and is called the 

 amniotic sack, or true amnion. The liquid which 

 it contains is called the amniotic fluid. The 

 outer membrane lies close under the vitelline 

 membrane and is called the false amnion, and 

 goes to make up the serous membrane of the 

 body. 



