130 BRAIN AND BODY OF FISH 



innervated by the glossopharyngeal nerve and here food is prevented 

 from passing into the post-nasal space ; the sentinel taste-buds of 

 epiglottis and pharynx are innervated by the vagus and thereby a 

 mechanism is called into play that prevents food entering the glottis. 

 It would appear that the central connections in the brain interpret 

 the sensations received in accordance with the area from which 

 the afferent impulses arise. 



In concluding these details of the facial lobe, it is necessary to 

 mention the large lateral nerve that conveys the gustatory impression 

 from the skin. The facial nerve has a ganglion called the facial 

 or geniculate ganghon ; into tliis the lateralis portion of the facial 

 enters ; it has the following branches each of which may have a 

 ganglion at its root a superficial opthalmic, a buccal and an external 

 mandibular branch. 



As regards the names of the prominent lobes of the medulla it 

 may be well to mention that the large bilateral lobes have been 

 called the lobus posterior and the pneumogastric lobe, while the 

 central lobe or anterior have been called the mediam lobe of Baudelot 

 or the " lobule mediane du Bulbe." The terms now in common use 

 are, the vagal lobe for the former and the facial lobe for the latter. 

 Herrick has made a detailed examination of the skin of a small 

 cat-fish and has prepared a diagram reproduced in many textbooks 

 of the distribution of the taste-buds over the external surface and 

 of the cuteneous branches of the seventh nerve which supply them. 

 A broad summary of the above facts relating to the lobes of the 

 medulla can be made in Herrick's words, " The vagal lobes for mouth- 

 tasting and facial lobes for skin-tasting are local enlargements of 

 the visceral sensory brain as is illustrated in the dog-fish. All the 

 taste-buds in the pharynx and back part of the mouth are supplied 

 by the vagal and glossopharyngeal nerves — those in front of the 

 mouth lips and outer skin from a root of the facial nerve which 

 apparently corresponds with the portio intermedia of human 

 anatomy." 



The whole matter is best summed in the words of Sir Charles 

 Bell, " an animal may have a particular organ developed and with 

 the external apparatus there is a corresponding or adjusted condition 

 of the appropriated nerve." 



