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POPULAR SCIENCE REVIEW. 
ing sense-impressions and of performing respondent movements ; and Dr. 
Terrier has shown that the application of Faradic electricity to the corpora 
striata (which, though wrapped up in the hemispheres of the human brain, 
do not really form part of them) calls forth movement in nearly all the 
muscles of the body, the flexors predominating over the extensors : while 
a like stimulation of the corpora quadrigemina (another pair of the same 
fundamental series) calls forth violent action of the extensor muscles. 
Among Dr. Ferrier’s most curious results is the control which the cerebellum 
is found to have over the movements of the eyeballs ; and it seems probable 
that its special influence on the balancing movements of the body is related 
to this control over the visual direction. Proceeding, then, to the cerebrum, 
the lecturer pointed out that comparative anatomy and embryonic develop- 
ment agree in showing that the cerebrum of a reptile or bird is not the 
miniature of that of man, but represents only its anterior lobes ; that in the 
lower mammalia the middle lobes sprout, as it were, from the back of the 
anterior ; and that in the quadrumana and man the posterior lobes sprout 
from the back of the middle. Thus, as it is the anterior lobe which is 
common to all creatures possessing a cerebrum, while the posterior is pecu- 
liar to man and his nearest allies, it is in the former, not the latter, that (if 
there be any localisation of faculties) we should expect to find those which 
man shares with the lower animals. This conclusion, which had been dis- 
tinctly drawn by the lecturer 25 years ago, is remarkably confirmed by the 
results of Dr. Ferrier’s experiments. The surface of the hemispheres of the 
brain in the rabbit and other rodents is smooth, or destitute of convolutions ; 
is formed by a thin layer of ‘ gray ’ or 1 cortical ’ substance, composed of 
nerve cells lying in the interstices of a very close reticulation of capillary 
blood vessels j and the 1 white ’ or medullary substance of the interior is 
composed of nerve fibres, which connect this cortical layer with the senso- 
rium beneath, and which also pass between the different parts of the cortical 
layer itself. In ascending the mammalian series, however, we find the 
cortical layer folded into plaits, by which its surface is largely increased, and 
these plaits form what are known as the 1 convolutions.’ They were for- 
merly supposed to be destitute of regularity, but the careful study of them 
by Leuret, Gratiolet, and others has shown that they are disposed on a 
regular plan, gradually increasing in complexity, which can be traced up- 
wards through the quadrumana to man. It was, untfi lately, the current 
doctrine of physiology that no stimulation of the cerebrum would excite 
either sensation or motion, but it has been recently found that the application 
of a galvanic current to the cortical substance calls forth movements ; and 
Dr. Ferrier has used with the best results the more intense Faradic current 
of an induction coil. The immediate effect of its application to the cortical 
substance was in all cases to produce an afflux of blood, shown by the visible 
distension of the vessels ; and to the augmented activity of the reaction 
between the blood and the nerve substance, producing an excessive tension, 
like that of an overcharged Leyden jar, rather than to the direct stimulation 
of the nerve-substance itself, the lecturer attributed the discharges of nerve- 
force which produced movement, the evidence of this being furnished by 
the time that was required (especially when the two electrodes, or poles of 
the battery, were far apart) to call forth the action, as well as by the frequent 
