I2 3 8 



THE SENSE OF TASTE. 



undoubtedly carries nerve fibres of taste from the back of the tongue, 

 whereas branches of the fifth are concerned in the transmission of 

 ordinary sensory impulses from this situation. M. v. Vintschgau and 

 Honigschmied 1 found that within a few months subsequent to the 

 division of the glosso-pharyngeal nerve in the rabbit, the bulbs entirely 

 disappeared on the side on which the division was made. 



While it is pretty evident that the bulbs are end-organs of taste, 

 and that they are the terminations of the taste fibres which pass up the 

 branches of the glosso-pharyngeal nerve, it is possible, of course, that 

 these fibres have other terminations as well. As regards the front of 

 the tongue where the bulbs are few in number, and where the taste- 

 fibres pass by the lingualis and 

 the chorda tympani, it is pro- 

 bable that here also the bulbs are 

 end-organs of taste, though again 

 they are not necessarily the only 

 end-organs concerned. 



In tracing the course of the 

 nerve fibres concerned with taste, 

 y from their origin in the tongue to 

 their terminations in the brain, it 

 will be convenient to commence 

 with those which spring from the 

 anterior portion of the tongue. 

 The paths followed by these fibres 

 are very complicated, and are still 

 to some extent doubtful. The 

 following account will be more 

 readily understood if reference be 

 made to Fig. 445. It is generally 

 admitted that the nerve fibres of 

 taste pass from the front of the 

 tongue in the lingual nerve, since 

 Fig. 445.— Horizontal lines indicate distribu- division of that nerve below the 

 tion of lingual including chorda tympani ; „ • . e ■ .• u ,1 i j 



oblique lints indicate distribution of glosso- P 0mt °? junction of the chorda 

 pharyngeal ; the larger circles indicate cir- tympani produces paralysis of 

 cumvallate papillae ; the smaller circles are taste On the same side. 2 The 



FiyngeT ^ ™* ^^ hy ^ ^P™' fibr es do not pass up in the lingual 



further than the point where the 

 chorda tympani joins it, for Erb 3 has shown that a lesion of the lingual 

 nerve above the point of junction of the chorda has no effect upon 

 taste. On the other hand, division of the chorda tympani, and disease 

 of the middle ear involving this nerve, lead to loss of taste on the 

 affected side. Hence there is little doubt that the taste fibres pass 

 from the lingual nerve into the chorda tympani on their way to the 

 brain. As regards the further course of the fibres, there is much con- 

 flicting evidence. According to some observers, the fibres pass again 

 into the course of the fifth nerve to reach the brain, while others 



1 Arch. f. d. yes. Physiol., Bonn, 1877, Bd. xiv. S. 443; Hermann's "Handbuch," 

 1879, Bd. iii. Th. 2, S. 145 ; also see F. Hermann, Centralbl./. Physiol., Leipzig u. Wien, 

 1877, Bd. ii. S. 503-4. * ' * * 



2 Mader, Centralbl./. d. mcd. Wissensch., Berlin, 1879, S. 395. 



3 Neurol. Centralbl., Leipzig, 1882, S. 104; also see F. Saltzer, Arch. f. klin. Chir., 

 Berlin, Bd. xxxvii. Heft 3. 



