310 ANATOMY OF THE DOMESTIC FOWL 



usually rich in blood-vessels; however, in the domestic fowls there 

 is in the comb, in the wattles, and similar appendages of the head, a 

 thick vascular network. 



The beak and the claws are modified skin; they are true horn mate- 

 rial. At the base of the beak there is often formed scales, which 

 surround the nostrils, in whole or in part, and have a naked, or 

 waxy, appearance, which is known as the cera. 



FIG. 79. Photomicrograph of the section of skin from the sole of the foot of 

 a hen. i, Horny stratified squamous epithelium, a, Stratum corneum. b, 

 Stratum lucidum. c, Stratum germinativum. 2, Connective tissue supporting 

 membrane, pars reticularis. 3, Blood-vessels. 



The feathers may be considered of two chief kinds, the quill 

 feathers and the clothing feathers. The most rudimentary of the 

 latter are known as down. A quill feather consists of two principal 

 parts: the quill, or calamus, and the vane, or vexillum. The quill 

 is continuous with the central shaft, called the rachis, the two form- 

 ing the stem of the feather. Projecting outward from the stem on 

 each side are a large number of pointed and very flexible barbs. 

 These barbs are located nearly at right angles to the quill and have 

 extending from them at right angles smaller processes or barbules. 



