500 ANIMAL PHYSIOLOGY. 
tion, situation, etc., of parts, will, however, be obvious, from 
the -figures themselves; and as we have already pointed out 
more than once, the preponderance of the cerebrum in man 
must ever be borne in mind in the consideration of his entire 
organization, whether physical, mental, or moral; or, to put 
the matter otherwise, all man’s functions are the better under- 
stood by the remembrance of this one fact, which will be at 
once illustrated when we consider the result of removal of the 
cerebrum in animals. 
ANIMALS DEPRIVED OF THE CEREBRUM. 
The cerebrum may be readily removed from a frog, without 
producing either severe prolonged shock or any considerable 
hemorrhage. Such an animal remains motionless, unless when 
stimulated, though in a somewhat different position from that 
of a frog having only its spinal cord. It can, however, 
crawl, leap, swim, balance itself on an inclined plane, and when 
leaping avoid obstacles. One looking at such an animal per- 
forming these various acts would scarcely suspect that any- 
thing was the matter with it, so perfectly executed are its 
movements. We are forced to conclude, from its remaining 
quiet, except when aroused by a stimulus, that its volition is 
lost; but, apart from that, and the fact that it evidently does 
not see as well as before, it appears to be normal. It has no 
intelligent directive power over its movements. It remains, 
therefore, to explain how it is that they are so much more 
complete, so much better co-ordinated in the entire animal than 
when only the spinal cord is left. It seems to be legitimate to 
infer that the other parts of the brain contain the nervous 
machinery for this work, which is usually stimulated to action 
by the will, but which an external stimulus may simulate. All 
the connections, structural and functional, are present, except 
those on which successful volition depends. The frog with the 
cord only, sinks at once when thrown into water; when gently 
placed on its back, it may and probably will remain in that 
position, without an attempt at recovery. There is, in fact, 
very limited power of co-ordination. 
Removal of the cerebral lobes in the bird is more likely to 
be attended with difficulties, and conclusions must be drawn 
with greater caution. 
But a pigeon may be kept alive after such an operation for 
months. It can stand, balancing on one leg; recover its posi- 
