448 PHYSIOLOGY 



brain causes pricking of the opposite ear, dilatation of the pupils, and rotation 

 of the head and eyes to the opposite side. It was stated by Ferrier that 

 ablation of the superior temporal convolution causes deafness, but Schafer 

 found that, even after extirpation of the superior temporal convolutions of 

 both sides, monkeys showed signs of hearing quite distinctly, and of under- 

 standing the nature of the sounds heard. One must conclude therefore that 

 the function of auditory perception is not entirely confined to the temporal 

 lobe, though its focal point may be located in the superior temporal con- 

 volution, especially in that part which is seated within the fissure of Sylvius. 



FIG. 233. Perimeter charts from right and left eye, showing the limitation of the field of 

 vision (right hemianopia) produced by a lesion of the left occipital cortex. (BECHTEREW.) 



This conclusion is strengthened by the results of clinical evidence in man, in 

 whom cerebral lesions, which have produced disturbances of auditory per- 

 ception, are found almost invariably to be closely associated with the superior 

 temporal convolution. 



SMELL AND TASTE 



The course of the fibres from the olfactory lobe may be used to throw 

 light upon the localisation of olfactory sensation in the cerebral cortex. 

 There is a great divergence between different animals in the degree to which 

 the olfactory sense is developed, and with this divergence we find corre- 

 sponding variations in the development of certain portions of the brain. 

 In those species with highly developed olfactory sense the following parts 

 of the brain show special growth : 



(1) The olfactory lobe, including the olfactory bulb, and the olfactory 

 tract. 



(2) The posterior part and the inferior surface of the frontal lobe. 



(3) The hippocampal gyms and the dentate convolution. 



(4) A convolution termed the gyms supracallosus and forming that part 

 of the gyrus fornicatus closely encircling the corpus callosum. 



(5) The anterior commissure. 



