8MELL 307 



though it were listening to a sound from the opposite 

 side. Lesions of this area in man are usually found to 

 be associated with deafness. In the monkey, however, 

 both superior temporal lobes may be removed without 

 causing any objective signs of deafness. It is beheved, 

 chiefly on histological grounds, that around this area of 

 the brain, which forms a receiving station for stimuh 

 (audito-sensory area), there is a large area, involving 

 probably the whole of the temporal lobe, concerned with 

 the higher psychical processes, such as the memory of 

 sounds. This is the audito-psychic area. It is connected 

 with the audito-sensory area by association fibres. 



4.— SMELL AND TASTE 



THE SENSE OF SMELL 



Compared with some of the lower animals, man has 

 but a poor sense of smell. Nevertheless his olfactory 

 nerves are remarkably sensitive. The olfactory sense- 

 organs are situated in the mucous membrane covering 

 the superior turbinate bone and the part of the septum 

 opposite. They take the form of bipolar cells, of which 

 the free distal processes project slightly below the general 

 level of the mucous membrane. Among these processes 

 are the columnar sustentacular cells and the serous glands 

 of Bowman, the latter serving to keep the sensitive nerve- 

 endings moist. The proximal processes of the olfactory 

 cells take the form of non-medullated nerve-fibres, which 

 pierce the cribriform plate of the ethmoid and enter the 

 olfactory lobe. 



Here they terminate in a rich arborisation in close con- 

 nection with the dendrites of the mitral cells, the arborisa- 

 tion of these two neurones forming the " glomeruli." The 

 mitral cells, whose cell-bodies are also situated in the 

 olfactory lobe, send axons into the fore part of the brain, 

 where they make extensive and ill-defined connections with 



