504 ANIMAL PHYSIOLOGY. 
first place, we very much doubt whether, in such an experi- 
ment, tactile and muscular sensation is in abeyance, and, in 
the second place, if it were, there are associated sensations, pos- 
. sibly from the vascular and lymphatic systems, and many 
other sources within, which can not be ignored. We do not 
even yet seem to be sufficiently alive to the delicacy and the 
immense variety of our sensations, some of which are abso- 
lutely indefinable; otherwise we do not think such experiments 
as that above cited would be adduced in proof of a special 
sense of equilibrium. 
Until further evidence is forthcoming, then, we are not in- 
clined to give assent to the existence of any mechanism in the 
semicircular canals, affording sensory data so entirely different 
from those furnished by other recognized (and unrecognized) 
sense-organs, that upon them alone, or in a manner entirely 
their own, arises a consciousness of equilibrium. We are in- 
clined to regard the latter as depending upon the fusion in con- 
sciousness of a vast complex of sensations; and that upon the 
whole being there represented, or a portion wanting, depends 
either the preservation of equilibrium, or a partial or entire loss 
of the same. Nevertheless, it is highly probable that sensory 
impulses of a very important character, in addition to such as 
are essential for hearing, may proceed from the semicircular 
canals, and indeed other parts of the labyrinth of the ear. 
ForcED MOVEMENTS. 
When certain portions of the brain of the mammal have 
been injured, movements of a special character result, and, 
inasmuch as they are not voluntary, in the ordinary sense at 
least, have been spoken of as forced or compulsory. The move- 
ments may be classified according as they are around the long 
vertical or the transverse axis of the body of the animal. Hence 
there are “circus ” movements, when the creattre simply turns 
about in a circle, “rolling” movements, etc. These and others 
may be toward or from the side of injury. While in some 
cases there may be a certain amount of muscular weakness in 
consequence of the injury, which may, in part, account for the 
direction of the movements, this is not so in all cases; nor does 
it, in itself, explain the fact of their being plainly not volun- 
tary in the usual sense. 
The parts of the brain, which, when injured, are most liable 
to be followed by forced movements are the basal ganglia (cor- 
