290 
REPORTS OF SOCIETIES. 
Dec., 1889. 
then described the results of further experiments on the accommoda¬ 
tion of the colour of lepidopterous pupae to their surroundings, showing 
how the reddish chrysalis of the large Tortoiseshell Butterfly, V. Poly- 
chloros, equally with the greyish chrysalis of the small Tortoiseshell 
V. TJrticce, and the usually green one of the Peacock, V. Io, was changed 
in colour harmoniously with the surroundings it was exposed to at the 
period of pupation, agreeing with these in sensitiveness to black, but 
differing from them in retaining something like uniformity when 
exposed to red surroundings (which are near to its own natural hue), 
in the presence of which the other two species are apt to vary widely 
between the extremes of light and dark forms. Mr. Pembrey followed 
in the same line, stating results chiefly from experiments with the 
pupas of V. lo, agreeing in the main with Mr. E. B. Poulton’s original 
experiments, but pointing to something in the direction of the influence 
of heredity in the preponderance of light or dark forms in individual 
broods under all surroundings.—Tuesday, November 19th. The Presi¬ 
dent in the chair. About sixty present. Mr. Gotch gave a most 
interesting lecture on the “ Functions of the Brain,” of which the 
following is only a very brief summary. Limiting his subject to the 
localisation of the motor functions, and to the physiological point 
only, the lecturer sketched and illustrated by diagrams and lantern 
slides the main facts of the nervous system, the conduction of sensory 
impressions and motory impulses (the latter setting muscles in motion) 
through nerve fibres from nerve cells, the two sets of fibres, though 
distinct in function being externally indistinguishable. He then 
illustrated the development in the ascending scale of animal life of 
the mass of nerve cells (ganglia) connected with eyes, mouth, &c., the 
chief sensorial organs into the cerebral hemisphere, or brain, and noted 
the physiological fact of the crossing of the nerve fibres, resulting from 
the bilateral symmetry of vertebrates in the transmission of impulse 
from right or left portion of brain to the opposite side of the body. 
A series of representations of the brain of different animals was shown 
to demonstrate that convolutions with their corresponding fissures, 
affording more surface, in which it was afterwards shown that the 
nerve cells existed, gave a relative increase of possibility of muscular 
excitation, and in connection with this, the brain of man, as compared 
with that of his nearest vertebrate kin, the monkeys, showed greater 
convolution. A vertical section of the human brain was then shown, 
and the seat of the nerve cells, the originators of muscular impulse, 
pointed out as being in the grey surface of the convolutions or cortex, 
as it is termed, differing both in substance and colour from the white 
nerve fibres (serving as conductors) underlying them. The practical 
outcome of the physiological theory was then dealt with. The relation 
of a series of experiments on the brain of monkeys, whose brain was 
exposed while under the influence of anaesthetics, and subjected to the 
excitation of currents of electricity, showed that different areas of the 
cortical portion induce muscular action in different members of the 
body, leading up to the fact that abnormal muscular action, such as is 
manifested in various diseases, e.g., epilepsy, is directly caused by 
abnormal conditions in a definite portion of brain-surface in which 
the impulse to this particular muscle originates. From this the main 
conclusion flowed naturally that by thus accurately localising the 
seat of mischief by experiments in corpore (comparatively) vili, the art 
of the surgeon, in treating cases of disease arising from brain affection 
in the human body, has received very great assistance from the 
physiologist, a fact which Dr. Collier and Dr. Sankey at the conclusion 
of the lecture bore testimony to, quoting instances in point. 
