182 Proceedings of the Royal Irish Academy. 



special part of the cortex, came to tlie conclusion that destruction of 

 Fen'ier's auditoiy centre, or even complete removal of the whole 

 temporal lobe, did not impair the animal's sense of hearing. 



Mean-«-hile the question had been attacked in another way. The 

 experiments of Baginski,^ who followed the degenerations re- 

 sulting fi'om destruction of the cochlea in rabbits, together with the 

 researches of Flechsig^ and Bechterew, who employed the now 

 well kaown embryological method of the former investigator, showed 

 that the auditoiy nerve of one side, is brought into connexion with 

 the posterior tubercle of the corpus quadrigeminum, and with the 

 internal geniculate body of the opposite side, by means of the 

 contralateral fillet. 



Prior to this, V. Ilonakow^^ who extirpated definite regions of 

 the cortex of the brain in new-born animals, and afterwards followed 

 the tracts of aiTested development which resulted fi'om these 

 operations, had come to the conclusion that fibres from the ventral 

 part of the temporal lobe end, some in the corpus genicidatum 

 internum, others in the posterior tubercle of the quadiigeminate body, 

 and still others pass directly down into the fillet. 



The difiiculties attendant upon the accui-ate tracing of conducting 

 paths within the brain prevented these results from being finally 

 accepted as conclusive, and since their publication many investigators 

 have engaged in work more or less intimately connected with this field. 



Helcl,^ who employed the newly introduced method of Marchi for 

 showing degenerated tracts, was enabled to fully confiiTa the 

 observations of Plechsig and Bechterew regarding the central con- 

 nexions of the auditoiy nerve. Yon Monakow, who likewise carried out 

 an investigation on this part of the subject, has also arrived at results 

 which, in the main, agree with those of Flechsig, Bechterew, and Held. 

 He takes a different view, however, regarding the paths which the 

 connecting fibres pui'sue in one part of theii' course, when passing 

 from the auditoiy nuclei to the above-mentioned ganglia. 



^ BaginsM, B. " Ueber d. Urspr. und centr. Yerlauf d. Keiv. acust. d. 

 Kanincliens." Virch. Archiv, 105, s. 28-46. 



'^Flechsig, P. (witli Bechterew). " Zur Lehre. v. centr. Yerlaiif d. Sinnes- 

 Nerv." Neurol. Centr., No. 23, s. 545-551. 



^ V. Ilonahoiv. "■ Ueber einige durch extirj^. cii'cumscr. Himiind-Reg. bedingt 

 Entwickelungshemm. d. Kanincli-Geliims." Archivf. Psych., xii. 1, s. 141 : also 

 xii., s. 535-549. 



^ Seld. "Die cent. Bahnen des Nerv. acust. bei d. Katze." Ai'chiv f. Anat. 

 u. Physiol., Anat. Abt, 1891. 



