FIBRES OF THE INTERNAL CAPSULE OF THE BONNET MONKEY. 73 
Analysis of Results, 
On pp. 60-63 we give, in Table T., the order of arrangement of the representation of 
different parts of the body. We cannot well separate the consideration of this 
arrangement from that of the order in which the different characters of the move¬ 
ments are placed, hence we will reserve to p. 79 tlie discussion of the facts set ont in 
Table I. 
We will, however, proceed to discuss certain points of general interest upon which 
a clear opinion must be formed before the main results of this research can be given 
at length. Of such points we take first, as the most important, the phenomenon of 
bilateral movement. 
Movements of Muscles of the same side as that stimidated. 
The phenomenon of bilateral movement occurring upon excitation of one hemisphere 
has often been approached from its theoretical, experimental, and clinical aspects. 
It has been assumed by Broadbent* that this is effected by the impulses passing 
from the sound hemisphere across commissural fibres postulated to exist between the 
lower [i.e., bulbo-spinal) centres of the two sides, and he explained the common mode 
of recovery from haemorrhagic compression and destruction of the internal capsule by 
this theory. This theory has been favourably received by neurologists as an expla¬ 
nation of the phenomenon of bilateral movement, but we submit that the subject can 
only profitably be treated upon experimental facts as a basis. 
Before any satisfactory conclusions can be arrived at, we must obviously first deter¬ 
mine exactly how much bilateral representation of movement exists in the cortex of 
a normal uninjured nervous system, and, in this case, of the Bonnet Monkey. Further 
we must understand clearly what we mean by bilateral representation. 
Beginning with this last, we mean that the same movement of symmetrical parts 
of both sides of the body is represented in one point of the cortex of both hemi¬ 
spheres, i.e., that excitation of such a point evokes simultaneous and identical move¬ 
ment in the same part of both sides of the body. 
In attempting to classify “bilateral movements” it is necessary to point out first 
that movements such as conjugate deviation of the eyes are not, strictly speaking, 
examples of bilateral representation. For while it is true both eyeballs move, never¬ 
theless one is rotated out, the other rotated in, and since this conjugate deviation 
occurs as the result of a single idea, the movement of both eyeballs really corresponds 
to that of one limb, and this is more especially the case since, as just said, the 
muscles employed on each side are different. A final confirmation of this view lies 
in the fact that excitation of one hemisphere produces conjugate deviation in one 
direction only, while excitation of the other evokes an exactly opposite movement. 
* ‘ BritisL Medical Journal,’ vol. 1, 1876, pp. 3.33, 371, 401. 
MDCCCXC.—B. 
L 
