DE. D. FEEEIEE ON THE BEAIN OF MONKEYS. 
471 
In the above-mentioned experiments both these convolutions were more or less con- 
jointly involved. 
Owing to this difficulty, I shall speak of the two together as the “ hippocampal fold,” 
and regard this as the seat of tactile perception. 
We are now in a position to differentiate the various effects on sensation caused by 
general destruction of the temporo-sphenoidal lobe. 
As regards hearing, separate evidence is given in Experiment XY. of the localization 
of this faculty in the superior temporo-sphenoidal convolution. 
The absence of reaction to the usual auditory stimuli, combined with the effects of 
stimulation of this convolution, afford evidence of the strongest possible character of the 
localization of this sense. 
The localization of smell is no less clearly indicated. Anatomically, the connexion 
between the olfactory tract and the subiculum cornu ammonis, though less evident in 
man, is clear in the monkey, and very apparent in the lower animals. 
The effects of irritation of this region are very constant and characteristic, and are of 
the same nature as direct irritation of the nostril or of the olfactory bulb itself. 
Destruction of this region causes abolition or diminution of reaction to stimuli on the 
same side as the lesion. 
Taken together, these facts establish the localization of the sense of smell in the subi- 
culum, or tip of the temporo-sphenoidal lobe. 
As to the sense of taste, the positive indications are less distinct than those of smell 
or hearing. 
Yet the phenomena occasionally observed on stimulation of the lower part of the 
middle temporo-sphenoidal convolution, viz. movements of the lips and cheek-pouches, 
may be taken in connexion with lesions affecting this region, and accompanied by loss 
of reaction to stimuli of taste, to afford evidence of no weak character for the localiza- 
tion of taste in or near this region. 
That the centres of gastatory and olfactory perception are closely related to each other 
anatomically is rendered probable by the fact, often observed, of loss of taste and smell 
following severe blows on the head, and particularly of the vertex. It is hot at all likely 
that one and the same cause should simultaneously directly affect all the nerves which 
are involved in the sensations of smell and taste ; but it is easy to understand that a 
contre-coup might readily affect the integrity and functional activity of the lower end of 
the temporo-sphenoidal lobe, in which the above experiments serve to localize the cen- 
tral seats of these faculties. 
We have thus accounted for the senses of sight, hearing, taste, smell, and touch, and 
given evidence for the localization of each and all of these in the central convolutions. 
Whether they are all integrated in the optic thalamus is a subject on which the 
experiments I have yet made do not furnish sufficient evidence; but the following 
experiment serves to prove that, in regard to tactile sensation, this is the case. 
