CHAPTER XV 

 THE ANATOMY OF GUSTATION 



G. H. Parker, of Harvard, in his monograph on smell, taste, and 

 alHed senses, says : " there are no separate gustatory nerves in the 

 vertebrates as there are olfactory nerves and optic nerves. Gusta- 

 tory fibres occur in several cranial nerves and it is by means of these 

 that the taste-buds of various regions are provided with those nervous 

 connections that have been described." The result of our study of 

 the distribution of the taste-buds in a large number of fish of differ- 

 ent species makes it clear that taste-buds, although as regards their 

 microscopic anatomy they are apparently similar, yet have functions 

 that vary accorchng to their central representation in the medulla 

 oblongata. Taste-buds supplied by the facial nerve have a true 

 gustatory function ; those supplied by the glossopharyngeal 

 nerves on the soft palate, etc., have a sentinel function, connected 

 with swallowing, and those supplied by the vagus have a sentinel 

 function designed to protect the lungs from food-stuffs, a directional 

 function. 



Taste, like smell, is a chemical sense, and the gustatory organs 

 enable the animal to recognise sweet, sour, salty, and bitter sub- 

 stances. Fish living entii'ely in a fluid medium must necessarily 

 be furnished with an extensive gustatory system and so we find 

 that certain families not only possess taste-buds over the whole 

 surface of the body, but have a peculiar comb-like organ with ridges 

 covered with taste-buds in the mouth known as the palatal organ. 



Recently the late Prof. A. E. Boycott, when examining the orifice 

 of the pneumatic duct which leads from the swim-bladder into the 

 gullet, noticed that there was a ring of taste-buds, and that these 

 guarded the entrance to an enlargement of the duct of an unusual 

 structure. This is known as the pneumatic bulb. 



This observation has been confirmed and described by myself in 

 the tench, and the significance of the existence of taste-buds in this 

 situation pointed out. Recent experiments by Damant and Evans 

 have proved conclusively that under normal conchtions fish with 

 a pneumatic duct, opening into the gullet, fill their swim-bladder by 

 coming to the surface and swallowing air, which is pumped into the 



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