452 
DR. D. FERRIER ON THE BRAIN OE MONKEYS. 
Experiment XI. 
December 10£A, 1873. — The left hemisphere of a monkey was exposed in the regions 
of the ascending parietal convolution, the postero-parietal lobule, the angular gyrus, and 
the upper part of the superior and middle temporo-sphenoidal convolutions. 
After experimentation by means of electric irritation on these regions, the temporo- 
sphenoidal lobe was deeply divided with the galvano-cautery in a line nearly coinciding 
with the direction of the lower temporal fissure (see fig. 13), and the substance of the 
superior temporo-sphenoidal and middle temporo-sphenoidal convolutions destroyed and 
scooped out throughout their upper two thirds approximately. 
After the operation the animal retained sight, and apparently heard as before, as 
judged by its reaction to sounds. 
The condition as to smell and taste is exceedingly difficult to determine accurately. 
As to smell, there is hardly any odour, pure and simple, which will cause distinct 
manifestation of olfactory sensation in a monkey ; and one must study the habits of the 
animal carefully, or employ some volatile substance which will cause reaction. These, 
however, such as ammonic and acetic acid, act conjointly on the nerves of common sen- 
sation and on the special nerve of smell. I have found, however, by careful experi- 
mentation on a patient who had lost both taste and smell as the result of a blow on the 
head, that ammonic and acetic acid, and particularly the latter, cause much less reaction 
than they do when both systems of nerves are intact. 
Confirmations of this will be found among the experiments narrated. 
The reaction to acetic acid, which I frequently used to test the sensibility of the nostrils, 
is only a comparative test, and reaction caused by it, when applied to the nostril, is not 
to be regarded as an indication of smell ; but the absence of reaction would show that 
the sensibility of the nostrils had been entirely lost ; while a less reaction in one nostril 
as compared with the other would fairly indicate some abnormal condition of the nostril, 
the exact cause of which is capable perhaps of explanation by other facts. 
In this case the reaction to the vapour of acetic acid w T as distinctly less in the left 
nostril than in the right. (The left nostril is, as will be noted, the same side as the 
lesion in the hemisphere.) 
As to taste, no exact experiment was made. The right side of the tongue was 
touched with a rod dipped in perchloride of iron; but, owing to the nature of the 
substance and the diffusion in the mouth, nothing could be ascertained accurately, though 
I thought that there seemed to be less immediate reaction on the right side than on 
the left. 
The animal had not lost its appetite, for it drank milk and ate some food offered to it. 
Hearing, as was noted, did not seem affected, as the animal reacted as usual to sounds, 
turning its head, &c. 
As the animal had, however, its left ear and right hemisphere intact, I plugged up 
the left ear securely by means of cotton-wool, in order to ascertain whether it heard 
in reality only with the right. 
