ANATOMY OF BIRDS 17 
left oviduct and equally voluminous. Its anterior extremity ex- 
hibited an infundibular membrane in contact with the ovary. Pos- 
teriorly it opened into the cloaca opposite the left oviduct. The 
appearance of its mucous membrane suggested that it was capable of 
functionating. 
The ovary is placed in the left sub-lumbar region, opposed on its: 
superior surface to the ribs. In fowls it contains from twelve to 
fifteen hundred germ cells in various stages of development from 
microscopic granules to fully formed yolks in functionating ovaries. 
The oviduct terminates in the urogenital division of the cloaca just 
anterior to the left ureter. It is divided into five regions, each of 
which has a specific function. The first region, the infundibulum, 
is a delicate membrane of a funnel-like form which receives the 
ovum. Succeeding this is the part secreting albumen followed by 
the isthmus which secretes the shell membrane. The uterus or 
fourth region forms the shell. The last region, the vagina, is short 
and is provided with a sphincter muscle at its entrance to the cloaca. 
SKIN AND ITS APPENDAGES 
The skin of birds is without sweat glands. There are some small 
glands in the exterior passage of the ear, which secrete an unctious 
fluid. There is also a protruding glandular organ located above the 
coccyx between the tail feathers and known as the uropygium or 
rump gland, an organ peculiar to birds. It is round or oval in 
form and is divided into two halves by a medial septum. The exit 
passage is through a teat-like cone which projects above the level 
of the skin. Two external orifices are observed in the gland of the 
duck. In hens the gland is about the size of a pea, in geese about 
as large as a hazel nut and in the swan about an inch and one half 
in length. Its function is to secrete an oily fluid for water-proofing 
and dressing the feathers. The secretion is taken up by the beak 
and spread over the plumage. 
The feathers are complicated modifications of epidermic struc- 
ture. Each feather is composed of a quill, a shaft and a vane. 
The quill is embedded in a feather follicle of the skin and extends 
outwardly to the point where the barbs of the vane arise. It has 
an opening at its base for the reception of the dermal papilla and 
another opening at its point of junction with the vane. The shaft 
continues the quill to the extremity of the feather. The vane con- 
sists of two rows of barbs which arise on opposite sides of the shaft. 
