248 



ANATOMY OF VERTEBRATES. 



part of the calyx, wliere tlie vessels become suddenly so minute, 

 as to seem to be wanting: fig. 128, c. This part, called the 

 ^stigma,' begins to appear when the ova have attained, in the 

 Common Fowl, the diameter of an inch: it increases in breadth, and 

 the membranes there become thinned, as the ovum acquires its 



Female organs, Fowl, at non-breediug season, 



Relation of the ova to tlie ovary in Birds, ccct: 



full size ; when they readily yield and are rent by the compressing 

 force of the infundibular opening of the oviduct, fig. 128, e, where- 

 upon the ovum slips out of the calyx into the efferent passage. 



The empty calyx collapses, as at h, b, fig. 126, and d, fig. 128, 

 rapidly shrinks, and is ultimately absorbed. 



In birds that have few young at a brood, as the Apteryx,^ 



' XI. vol. iii. 1'. 310, 1)1.36. 



