308 ANATOMY OF THE DOMESTIC FOWL 



feathers. They occur in large numbers in the periosteum of the 

 anterior tibial region and in the mucous membrane of the cloaca and 

 of the generative organs. They are numerous in the conjunctiva 

 and on the surface of the tongue. They are also found in the gums 

 and in the beak. 



Herbst's corpuscle is made up of a central fiber-shaped part with 

 a smooth extension of the axis cylinder of its nerve (Fig. 29, (7). 

 This central fiber is surrounded by a peculiar protoplasmic body. 

 Outside of this there is a double row of cubical cells which surround 

 the axial part. These are close together. Outside of these there 

 occurs a concentric lamellar layer, which contains cells. In the 

 periphery these lamellae become more distinct and contain larger 

 but fewer cells. The capsule is made up of very thin layers, which 

 are continued into the perineural layer. Each body contains a 

 thin outer zone. The nerve fiber passes in a regular manner from 

 the axis cylinder, the myelemma, and the sheath of Schwann, and 

 as a delicate nerve twig is surrounded by a sheath consisting of 

 several perineural layers. As it enters the center of the touch cor- 

 puscle, it loses its myeline sheath near the base of the body, and the 

 terminal fiber becomes flattened. Its rim is directed toward the 

 two rows of cubical cells, and it ends in a rounded knob. 



The touch corpuscles are the largest in the mucous membrane of 

 the cloaca and smallest in the skin. Hess has found these touch 

 corpuscles in the large filiform papillae on the side of the tongue 

 and a few on its lower surface. They are also found in the soft skin 

 of the edges and inner borders of the beak. 



