Landacre, Taste Buds of Arnciiiriis. 5 



of structural differences in their components and peripheral dis- 

 tribution, made the first successful attempt at such an analysis 

 on the sensory portions of the cranial nerves of the tadpole of 

 the common frog. As a result of this analysis Strong found that 

 the sensory portions of the V, VII, VIII, IX and X nerves could 

 be resolved into three components. 



1. The general cutaneous component, characterized periph- 

 erally by having medium sized fibers and free nerve endings, and 

 centrally by ending in the spinal fifth tract which is a continua- 

 tion of the dorsal horn of the cord. 



2. The acustico-lateralis component, characterized peripherally 

 by having coarse fibers and innervating the ear and lateral line 

 and related organs, and centrally by ending in the tuberculum 

 acusticum. 



3. The communis component, characterized peripherally by 

 innervating unspecialized mucous surfaces and specialized or- 

 gans in the form of terminal or taste buds, by having fine fibers, 

 and centrally by ending in the lobus vagi and lobus facialis, which 

 are really one nucleus morphologically. 



Strong's work was followed and confirmed in all essential 

 details by that of Herrick on Menidia ('99), on Gadus ('00), 

 on Ameiurus ('01); and by Cole on Gadus ('98) and on Pleuro- 

 nectes ('01); and by Coghill on Amblystoma ('02) and on Tri- 

 ton ('06); and by Johnston on Acipenser ('98) and on Petromy- 

 zon ('05), and others, so that we have a thorough knowledge of 

 the components of the cranial nerves based on a careful micro- 

 scopic study of serial sections for the cyclostomes, teleosts and 

 amphibia. In all these papers the necessity of correlating the 

 peripheral distribution of the nerve with its central endings and 

 the unraveling of the nerve throughout its whole course has been 

 kept in mind and accomplished with sn unexpected degree of 

 success. A study of the central endings of the cranial nerves in 

 the medulla and their homologies with the centers of the four roots 

 of Gaskell has been made particularly by Kingsbury ('95a, '97) 

 and by Johnston ('98, '01, '02a), in addition to the papers men- 

 tioned above, while the larger problem of the morphology of the 

 vertebrate head has been attacked by Johnston ('05b) from the 

 functional standpoint and in accord with the work on nerve com- 

 ponents. 



Since taste buds are innervated wherever situated exclusively 



