THE OLFA CTOR Y AND G USTA TOR Y AREAS. 763 



this again by the lateral fillet and by some fibres of the reticular formation 

 with the cochlear nerve. Flechsig a finds that in the child of tAvo months, 

 fibres are found undergoing myelination within the temporal lobe, connecting 

 the mesial geniculate body almost exclusively with the transverse convolutions 

 of the temporal lobe which are concealed within the Sylvian fissure. He regards 

 these as the only corticipetal fibres concerned with audition, and is on this 

 account disposed to locate the auditory area of the cortex in man exclusively 

 in this situation, although apparently willing to admit that corticifugal (motor) 

 fibres, set in activity by auditory impressions, may emerge from a larger area. 

 He describes a bundle of such fibres as passing from the temporal lobe by 

 way of the lateral fourth of the crusta to the pons Varolii (temporo-pontine 

 tract), and regards these as motor, carrying impulses for the movements of the 

 ears, head, and trunk. The opinion that the fibres in question are respectively 

 corticipetal or corticifugal rests, however, wholly upon the fact that those 

 regarded as centripetal are developed at a relatively earlier period than the 

 others. According to Held, although most of the fibres of the cochlear 

 (auditory) nerve are interrupted in the dorsal and ventral auditory nuclei, 

 the superior olivary nuclei of the same side, and the nuclei of the trapezium, 

 of the fillet, and of the inferior quadrigeminal body of the opposite side, some 

 fibres may pass directly to the cortex of the temporal lobe of the opposite side. 2 



Localisation within the auditory area.— Clinical evidence appears to 

 point to the fact that the appreciation of words heard is intimately associated 

 with the integrity of the first temporal gyrus of the left side, numerous 

 cases having been recorded of "word-deafness" resulting from lesions of this 

 convolution, especially of its posterior two-thirds. 3 Luciani and Sepilli 4 

 collected twenty cases of word-deafness, and of these fourteen were associated 

 with lesions more or less extensive of the first and second temporal gyri on 

 the left side of the brain. 5 



Munk states that in dogs in which the anterior part of the auditory area 

 is destroyed there is deafness for tones of high pitch, while destruction of the 

 posterior part of the area is attended by deafness to tones of low pitch. These 

 statements are confirmed and amplified by v. Bechterew and Larionofl', Avho 

 divide the auditory area into three zones, for high, medium, and low-pitched 

 notes respectively. But the difficulties of such experiments are so great, that 

 it would be wise to suspend one's judgment before accepting them as evidences 

 of intra-areal localisation. 



The olfactory and gustatory areas of the cerebral cortex. — 

 As Ferrier remarks : " The position of the olfactory centre may with great 

 probability be inferred from anatomical considerations alone, apart from 

 actual experiment." If with Broca we divide animals into those with a 

 highly developed olfactory sense (osmatics, including the great majority 

 of mammals) and those with feebly developed olfactory sense (anosmatics, 

 including the monkey, man, and a few amphibious or marine mammals), 

 we find that the parts of the brain which vary in development directly 

 with this sense are — (1) The olfactory lobe (olfactory bulb and tract); 

 (2) the posterior portion of the inferior surface of the frontal lobe ; (3) 

 the anterior portion of the hippocampal region, including the uncus, the 



1 " Localisation der geistigen Vorgiinge," etc., 1896. 



2 H. Held, Arch./. Anal. u. Eniwcklngsgesch., Leipzig, 1893, S. 201. 

 3 Naunyn, Vcrhandl. d. vi. Cong./, innere Med., Wiesbaden, 1887, S. 132. 



4 Quoted by Laquer {Neurol. Centralbl., Leipzig, 1888, S. 337), who also gives the 

 details of a well-observed case in which the lesion was strictly limited to the first 

 gyrus. For other cases bearing on this subject, see Ferrier, " Cerebral Localisation," 1890. 



8 Manouvier found the right superior temporal gyrus to be small in a man who was from 

 infancy deaf in the left ear (Bull. Soc. dc psycho/,, physiol., Paris, 1890, tome v.). See also 

 a case related by C. K. Mills in Brain, London, 1891, vol. xiv. p. 465. 



6 Arch. f. Physiol., Leipzig, 1899, S. 391. 



