vn] Limhif Lolx' and Olfactory Ana 191 



of smell were falsely interpreted. In Jackson and Beevor's case of tumour of the tip of the 

 temporal lobe involving the anterior end of the lobus pyriformis and the nucleus amygdalae 

 the patient was constantly afflicted with "a sense of horrid smell," and the authors are 

 probably correct both in regarding the disturbance as an irritative phenomenon and in 

 surmising that if the growth had been so extensive as completely to destroy the lobus 

 pyriformis, the sense of smell would have been altogether abolished, at any rate on that 

 side. Cases recorded by Churton and Griffiths, James Anderson and others point to a similar 

 conclusion, and also to the likelihood that the sense of taste is located in the precincts 

 of the same region. Bechterew, however, relates a case in which destruction of the uncinate 

 gyms and cornu ammonis was not associated with any disturbance of the gustatory sense, 

 and he consequently states that the hippocampal lobe cannot contain the taste centre, and 

 gives it as his opinion that this function is located on the outer surface of the operculum, 

 a view which he shares with one of his pupils, Gorschkow. Here, however, reference must be 

 made to an early negative case recorded by Bartels ; it was one of sarcoma of the brain: and 

 although the anterior two-thirds of the first, second and third temporal and occipito-temporal 

 gyrus (lobus pyriformis) along with the hippocampus and uncus in the left hemisphere were 

 destroyed, there was no noticeable impairment of the sense of smell. 



A critical analysis of these clinical cases shows that while they provide confirmatory 

 evidence of the localisation of the olfactory sense in the gyrus hippocampi, they admit of 

 no conclusions as to the precise position of the olfactory centre, and the information they 

 supply concerning the gustatory centre is still more meagre. 



Teachings of Comparative Anatomy. 



There is little doubt that studies in comparative anatomy, in showing the phylogenetic 

 importance of the lobus pyriformis, originally provided one of the strongest clues to the 

 localisation of the olfactory sense. 



It is many years since Broca and also Zuckerkandl demonstrated that in animals with 

 a highly-developed sense of smell this division of the hippocampus swells into a large 

 pear-shaped lobe, that in some animals (the horse, tapir, and rhinoceros) it is slightly 

 fissured, and that in all it is divided off from the rest of the temporal lobe by the fissura 

 rhinica, which although small and insignificant in the human brain is of great length and 

 depth in these osmatic animals. Both Broca and Zuckerkandl also extended the olfactory area 

 to the gyrus fornicatus, on account of the relatively strong development of this part in 

 osmatics ; and in support of this localisation Zuckerkandl relates how an examination of the 

 brains of two infants born without olfactory lobes revealed arrested development of the 

 uncinate gyrus, the cornu ammonis, and the anterior part of the gyrus fornicatus. 



It is unfortunate, however, that all comparative anatomists are not in agreement regarding 

 the localisation of this function ; thus Hill, who has written authoritative papers on the 

 subject, is careful to point out that in some anosmatic animals for instance, the Narwhal, 

 an animal entirely devoid of the sense of smell the lobus hippocampi attains a moderate 

 degree of development, and on the strength of this he believes, and his argument seems 

 a fair one, that this lobe cannot exist for the control of this function solely. In this 

 relation Hill attaches far more importance to the fascia dentata (gyrus dentatus) of the 

 cornu ammonis, stating that it is the only structure in this region which is wholly wanting 



