152 DE. C. E. BBEVOR AND MR. V. HORSLEY ON THE EXCITATION OF THE 
3. The chief fact in this connection, and indeed possibly the most important new 
point observed in this investigation, is the frequent limitation of movement to one 
segment when a point is excited, instead of, as in the Bonnet, a sequence of move¬ 
ments being thus produced. As an extreme instance of this singularity of function 
we may mention square 31, wdiere flexion of the elbow and nothing else was obtained. 
The elbow in the Macacque, it will be remembered, was never unaccompanied by 
movements of other segments and rarely initiated a “ March,” whereas in the Orang 
we found it represented absolutely alone. (See “Marches,” p. 144.) 
It is well known that in the lower orders of animals the integration of representa¬ 
tion becomes less perfect as we descend in the scale* * * § —that, in fact, it is increasingly 
diflicult to differentiate the areas for the limbs; while, on the contrary, in ascending 
the scale, we have shown in our previous communications that it is easy to differen 
date between the areas of representation of even the segments of the limbs; and 
finally, when we now arrive at the Orang, the segments are not only differentiated in 
representation, but the nature of that representation is that of single movements. 
There is now, from direct observation, reason to believe that in Man a similarly 
interrupted mode of representation exists. 
The excitability to faradic stimulation of the human brain was established by the 
observations of BartholowI and Sciamanna.| 
The detailed results, however, are not sufficiently accurate to throw light upon the 
present question. Four observations, however, have been made under more favour¬ 
able circumstances, although they cannot be fully accepted as deciding this question. 
I. In October, 1886,§ one of us (V. H.) explored (under anmsthesia, with morphia 
i”d gi’- chloroform), for purposes of exact localisation, the right facial area in a 
boy, the subject of epileptic attacks, and found that excitation with an interrupted 
induced current of a strength just felt by the tongue only produced movements in the 
opposite (left) side of the face at points distant from each other, and not at interme¬ 
diate points. In this case, however, the surface of the brain had been freely irrigated 
with 5 per cent, carbolic acid solution in water. The application of this lotion 
Professors Schafer and Horsley had already found to soon depress the excitability 
of the cortex. This observation, therefore cannot stand alone. 
II. In May, 1888, Dr. Keen of Philadelphia!! excited (under anaesthesia with 
morphia -g- gr. and ether) with a faradic current of sufficient strength to cause 
contraction of the muscles of his own hand, the cortex in a man also the subject 
of epilepsy, and obtained movements as follow's— “ The wrist (as observed by Morris 
•J. Lewis) moving in extension in the mid line and to the ulnar side at different 
* Fereier, ‘Functions of tlio Brain.’ 
t Bartholow, ‘ Amer. Joniai. Med. Sciences,’ April, 1874. 
t ‘Arcli. cli Psicliiatria e Scienza Penale,’ 1882, 
§ ‘ Brit. Med. Journ.,’ April 23, 1883. 
II ‘International Journal of Medical Science,’ 1888. 
