ESTHESIOLOGY 307 



apertures by which the air from the Eustachian tube is conducted to 

 the precranial diploae. 



THE ORGAN OF SMELL 



The nose is the seat of the peripheral portion of the organ of the 

 sense of smell. The terminals of the olfactory nerves, which receive 

 the impressions of odors, are broadened in the mucous membrane of 

 the walls of the anterior nares. There are no ethmoidal volutes, or 

 sieve-like structure, in birds. The nerve extends from the anterior 

 portion of the brain in cone-shape, finally dividing into filaments 

 which are distributed over the mucous surface of the turbinated 

 bones. 



THE ORGAN OF TASTE 



The most important part of the organ of taste is the tongue. 

 In birds the dorsum of the tongue is covered by a thick stratum 

 corneum, a heavy layer of stratified squamous epithelium. The 

 tongue, therefore is not in birds so well adapted for the perception 

 of taste as it is in mammals. The lingual branch of the trigemini 

 is lacking in birds. This fact makes the ninth pair, or the nervi 

 glosso-pharyngei, the exclusive nerves of taste. There is an opinion 

 ventured by one anatomist that, since the first and the second branch 

 of the fifth pair, or trigemini, have terminal filaments in the hard 

 palate, they may furnish fibers for the sense of taste. There are 

 many taste cells on the tongue and on the dorsal palate. 



THE ORGAN OF TOUCH 



The peripheral parts of the organ of touch in the fowl are the skin 

 and the feathers. 



In a few birds special touch and taste perception can be supplied 

 by the edge and point of the beak. 



In the skin of birds are found numerous sensory nerve endings for 

 tactile sense. 



The sensory nerves, which provide the sense of touch, usually 

 terminate in one of two forms. The first are the Herbst's bodies, 

 which in many respects are similar to the Picinian bodies. 



Herbst's touch corpuscles are found on all parts of the skin; they 

 are especially numerous in the region of the tail and of the wing. In 

 the wing they are particularly numerous in the region of the flight 



