MINUTE ANALYSIS OF CORTICAL CENTRES. 
157 
Table 1. 
Ferrier’s Centre. 
Authors’ Centre. 
Ferrieu’s Besult. 
3 
12, r 
Movements of the tail, generally associated 
with complex movements of thigh, leg, and 
foot, with adapted movements of the trunk 
by which the foot is drawn to the middle 
line of the body, as when the animal grasps 
with its foot or scratches its chest and 
abdomen. 
4 
i 
Retraction, with adduction of opposite arm, 
9 
(?) 11 
palm of hand being directed backwards. 
This action ... is such as maybe ascribed 
to the latissimus dorsi. 
6 
3 
Supination, flexion of forearm by which the 
3' 
4 
hand is raised to the face. 
a 
4' 
7 
Individual and combined movements of the 
b 
>7 ! 
< 
fingers and wrist, ending in clenching the 
c 
8 
fist. Centres for the extensors and flexors 
d 
behind 8' 
of individual digits could not be differen¬ 
tiated, but the prehensile movements of the 
opposite hand are evidently centralised here. 
We will now proceed to describe our method of experimentation, the results in full 
detail, and the generalisations which can be deduced therefrom. 
Method of Experimentation .—The animal being thoroughly anaesthetised with 
ether, the left cortex was exposed lege artis, and the dura mater raised. A careful 
drawing was then made of the arrangement of the sulci, upon which was represented 
the position of the various points stimulated. The cortex, after being carefully dried 
to prevent diffusion of the current, was excited as follows. The apparatus employed 
was one Daniell cell and an ordinary du Bois-Reymond coil, but no attempt was 
made to equalise the make-and-break shock by means of a Helmholtz wire. The elec¬ 
trodes were the ordinary platinum pattern, and were 2 mm. apart. The coil consisted 
of a primary bobbin wound round an iron core, with secondary bobbin sliding on a 
sledge over it, the distance between them being registered in centimetres, so that 
the strongest current would be at zero when the secondary coil completely covered 
the primary one. The primary current was interrupted by means of an ordinary 
Neef’s hammer, and the secondary currents with this arrangement were of a strength 
sufficient to produce the sensation of slight pricking on the human tongue when the 
secondary coil was at 8, i.e., 8 cm. from the primary. This very weak secondary 
current" was always employed so as to obviate the fallacy of diffusion. That this 
object was attained was obvious, for, if a certain movement was always obtained at 
one place, shifting the position of the electrodes for even one millimetre was sufficient 
to produce a totally different result. 
* This was the weakest current which would produce a contraction in the muscles. 
