26o THE BIOLOGY OF BIRDS 



has shown (1910) that this walling off of the ovary tends to 

 direct liberated ova into the mouth of the oviduct. Apart 

 from the musculature in the wall of the oviduct, some im- 

 portance in moving the egg downwards is also to be attached 

 to the dorsal and ventral bands, partly muscular and partly 

 ligamentar, which run from the oviduct to the wall of the 

 body-cavity. 



The best description of the bird's oviduct is that given 

 by F. M. Surface (19 12) in reference to the hen. As the 

 matter is very important in connection with the equipment 

 of the egg, some details must be given. 



The internal surface of the oviduct is thrown into a 

 number of primary longitudinal ridges, over which the 

 epithelium forms secondary folds. In the region badly 

 called the uterus, the ridges as such are lost, but their place 

 is taken by a number of leaf-like folds. 



The first region is that of the funnel which grips the ovum 

 liberated from the ovary by the bursting of a follicle. 

 Anteriorly it shows " glandular groves," accumulations of 

 gland-cells at the bottom of the grooves between the 

 secondary folds of the epitheUum. Further back it shows 

 unicellular glands among the ciliated cells. These uni- 

 cellular glands occur in all parts of the oviduct except the 

 anterior portion of the funnel. The funnel glands perhaps 

 secrete the chalaziferous layer — a very thin layer of dense 

 albuminous substance next the yolk. 



The second region is the coiled albumen region, with a 

 thick layer of " tubular glands," consisting of long con- 

 voluted and branched tubules, opening into the lumen of the 

 oviduct by short epithelial ducts and secreting large quanti- 

 ties of albumen. They are homologous with the glandular 

 grooves of the anterior portion of the funnel, and they occur 

 in all parts of the oviduct between the funnel and the vagina. 

 There are also, as already indicated, unicellular glands 

 among the ciliated cells. These two sets of glands form the 

 dense albumen outside the chalaziferous zone. 



The third region is known as the isthmus ; it is separated 

 off from the albumen region by a line without tubular 



