40 POULTRY LABORATORY GUIDE 



grapes, the external appearance being that of a 

 granular body attached to the spine by a folding 

 of the peritoneum. The nodules or ovum will 

 be seen irregular in size, some small and white, 

 and as they develop becoming large and yellow- 

 ish. 



Remove one of the largest ova, and examine 

 it for the following characters. The develop- 

 ment of the ovum is caused by the accumulation 

 of 'the yellow or yolk food, which causes a dis- 

 tention of the ovarian sack or calyx that encloses 

 the ovum. As it develops this yolk sack be- 

 comes more or less separated from the ovary and 

 forms a complete covering for the ovmn, remain- 

 ing attached to the ovary only by a narrow base 

 or stem called a pedicle. The calyx or yolk sack 

 will be seen to consist of two membranes joined 

 together by connective tissue and blood vessels. 

 These blood vessels seem to end in a transverse 

 white line which crosses the largest part of the 

 calyx. This band is called the stigma, and begins 

 to appear when the ovum is well developed, and 

 when fully developed the calyx gives way along 

 this line and the egg shps from its capsule and 

 passes into the enlarged funnel-shaped opening 

 of the oviduct. The empty sack collapses, 

 diminishing in size rapidly until it is finally 

 absorbed. 



