IV 



THE SENSE OF SMELL 



165 



who was destitute from birth of any sense of smell, and in whom 

 the post-mortem examination revealed absence of the olfactory 

 nerves. Diemerbrok and Mery attributed the capacity of per- 

 ceiving 'smell to the nasal branches of the fifth nerve as well, but 

 without convincing the majority of physiologists, by whom the 

 function is attributed wholly to the olfactory surface. 



Bellingeri (1818) and Cloquet (1828) supported this view. 

 Magendie, on the contrary, sought by numerous publications 

 (1824-41) to revive the earlier view of Diemerbrok and Mery, 

 and stated that no positive proof was forthcoming to show that 



FIG. 67. Diagram of the connection of cells and fibres in the olfactory bulb. (E. A. Schafer.) 

 olf.c., cells of the olfactory mucous membrane; olf.n., deepest layer of the bulb composed of 

 the olfactory nerve -fibres, which are prolonged from the olfactory cells; gl., olfactory 

 glomeruli, containing arborisations of. the olfactory nerve-fibres and of the dendrons of the 

 mitral cells ; m.c., mitral cells ; a, their axis-cylinder processes passing towards the nerve-fibre 

 layer, n.tr., of the bulb to become continuous with fibres of the olfactory tract; these axis- 

 cylinder processes are seen to give off collaterals, some of which pass again into the deeper 

 layers of the bulb ; ri, a nerve-fibre from the olfactory tract ramifying in the grey matter of 

 the bulb. 



the other nerves to the nasal rnucosa (sensory branches of the 

 trigeminus) did not participate in the function of smell. But he 

 evidently interpreted as effects of olfactory sensation the reflex 

 acts that can be excited in dogs deprived of the olfactory nerves, 

 by means of irritating vapours capable of acting on the tactile and 

 sensory nerves of the nasal mucous membrane. This was demon- 

 strated by Eschricht, Bell, Bishop, Joh. Miiller, Duges, and Picht. 

 The two last observers, who had no true olfactory sensibility, 

 were susceptible to the excitation due to the vapours of acetic 

 acid, ammonia, and the like, which provoked sneezing. Bidder, 

 Wagner, Longet, Vulpian, pronounced against Magendie's opinion ; 



