POULTRY LABORATORY GUIDE 41 



Make an outline drawing of a fully developed 

 ovum. 



The oviduct is a white tube which during the 

 breeding season is larger than the largest intes- 

 tine, covered with a network of branching blood 

 vessels. It starts near the ovary with an en- 

 larged funnel-shaped opening, and follows a 

 curved course, being bent upon itself three times, 

 finally reaching the cloaca, where it opens. 



When the ovum enters the oviduct it consists 

 of a yolk or vitellus enclosed in a thin vitelhne 

 membrane. Immediately upon its entering this 

 organ fertilization takes place, and it is pro- 

 pelled by the peristaltic contraction of the duct 

 toward the cloaca with a rotary or revolving 

 motion. The passage of the ovum stimulates 

 the membranes to secrete three layers of albumen 

 as it moves along, the first one being dense and 

 rich, containing threadhke forms connected at 

 each end which hold the yolk in place. These 

 threadhke pieces are called chalazse, and are 

 twisted in opposite directions by the rotations of 

 the ovum. Each of the following layers of al- 

 bumen is thinner and more watery than the 

 ones which preceded it. \ 



When the ovum reaches the small part of the 

 oviduct two dense layers of albumen are added, 

 which form the inner and outer shell membrane. 



