LESION OF DIFFERENT REGIONS OF THE CEREBRAL HEMISPHERES. 533 
lobes, was any defect discoverable in tbe domain of tactile or general sensibility. I 
bad in my previous researches (Philosophical Transactions, Yol. 1G5, Part 2) arrived 
at the same results, and I described how, after various experiments in which the 
hippocampal region—including in this the cornu ammonis and gyrus hippocampi or 
uncinate gyrus—became implicated in destructive lesions, and in which impairment or 
abolition of tactile sensibility was observed, experiments were devised with the view 
of destroying this region primarily. The method adopted was to pass a wire cautery 
through the extremity of the occipital lobe downwards and forwards in the direction 
of the hippocampal region. In two of the experiments, XVII. and XVIII., tactile 
sensibility was almost if not entirely abolished after this operation ; in the latter case 
directly, and in the former, in which the hippocampal region became implicated in the 
destructive softening, on the third day after the operation. 
As the validity of these experiments has been disputed on the ground that the 
posterior or sensory division of the internal capsule may have been involved in the 
lesion, I have re-investigated the position and extent of the lesions in these cases, the 
brains having been carefully preserved in spirit. 
Before the brains were cut in sections, drawings were made by Mr. Collings of the 
appearances presented by them. 
Plate 28 shows photographs of the drawings of No. XVII. ; fig. 87 being a drawing 
of the anterior half of the left hemisphere, and fig. 88 being the appearance presented 
by the under surface. In fig. 88, the point of emergence of the cautery is well seen— 
quite external to the gyrus hippocampi ; and in fig. 87, the total breaking down of 
the hippocampal region is indicated. On the upper surface of the lateral lobe of 
the cerebellum is a superficial groove indicating where it was grazed by the cautery. 
Figs. 89-94 are a series of sections of the hemisphere, cut transverse to the antero¬ 
posterior axis, arranged from behind forwards, beginning with the posterior cornu of 
the lateral ventricle, and ending with the head of the corpus striatum and anterior 
extremity of the temporo-sphenoidal lobe. Not a trace of the hippocampus major was 
found in any of the sections, and the gyrus hippocampi where it remained was in the 
form of a thin shell. All the medullary fibres of the hippocampal region, and also of 
the inferior temporo-sphenoidal convolutions were broken down and fell as debris out 
of the sections. The medullary fibres passing into the superior temporo-sphenoidal 
convolution were not destroyed, but they frequently broke through as seen in figs. 91 
and 92 during the cutting and mounting the sections. 
But the internal ganglia,* the crus cerebri with the section of the optic tract, and 
the internal capsule were absolutely uninjured, as may be seen in the various sections. 
Only those fibres descending towards the hippocampal and inferior temporo-sphenoidal 
regions were destroyed, and the corresponding fibres of the posterior cornu. 
The drawings in figs. 95 and 96 represent the under surface of the posterior half of 
* The whitish spots seen on the lenticular nucleus in fig. 93 are caused by portions of parafin used for 
embedding adhering to the edges of the section and slipping underneath in mounting. 
