LESION OF DIFFERENT REGIONS OF THE CEREBRAL HEMISPHERES. 507 
Horizontal sections were made of the hardened brain, of which a series of sun-prints 
are seen in Plate 22, figs. 32-38, arranged from above downwards. 
These show that the lesion was strictly confined to the cortex and medullary con¬ 
nexions of the superior temporo-sphenoidal convolution. 
Fig. 32, on a level with the island ofPEiL, shows no trace of the superior temporo- 
sphenoidal convolution. Fig. 33 shows a minute remnant of the medullary fibres and 
cortex. Fig. 34, at the upper extremity of the triangular portion of cortex adherent 
behind the fissure of Sylvius, shows that the medullary fibres have been completely 
severed. Figs. 35 and 36, on a level with the anterior commissure, show similar appear¬ 
ances ; while figs. 37 and 38, at the lower extremity of the temporo-sphenoidal lobe, 
where the lesion was deepest, show that it did not penetrate beyond the medullary 
fibres of the superior temporo-sphenoidal convolution. 
The right hemisphere. —The membranes were adherent over the lower extremity of 
the posterior limb of the angular gyrus and adjacent margin of the occipital lobe, and 
over the region corresponding to the upper half of the superior temporo-sphenoidal 
convolution. The cortex was entirely destroyed, and the medullary fibres severed 
here, leaving a groove. At the lower half of the superior temporo-sphenoidal convo¬ 
lution the cautery burrowed beneath the cortex without destroying it superficially, 
but undermining it and causing considerable reduction in superficial extent as com¬ 
pared with the normal. A series of sun-prints of horizontal sections is given in 
figs. 25-31. 
Fig. 25, through the upper portion of the lesion, shows the temporo-sphenoidal con¬ 
volution destroyed with the exception of a narrow strip immediately posterior to the 
fissure of Sylvius. Fig. 26, at a lower level, shows the medullary fibres completely 
severed. Figs. 27, 28, and 29 present similar appearances, showing the sinus made by 
the cautery, hollowing out and almost completely severing the medullary fibres of the 
superior temporo-spdienoidal convolution; while in figs. 30 and 31 the sinus only 
undermined the posterior half of this convolution. 
Remarks. —This case shows that bilateral destruction of the superior temporo- 
sphenoidal convolution causes loss of hearing without any other defect either in the 
domain of motion or sensation. The fact of deafness in this animal was admittedly 
established before the Physiological section of the International Medical Congress 
in 1881. 
The position of the lesion is proved by the photographs and sections to be in the 
cortex and medullary fibres of the superior temporo-sphenoidal convolutions, where it 
was stated to be. On the left side the destruction was most complete; on the right 
the destruction was not quite complete at the lower half. But the destruction was 
sufficient to cause such loss of hearing that no evidence could be obtained free from 
doubt that this continued even in a slight degree. 
3 t 2 
