JUNE 6, 1884.] 
ence of mental symptoms, which may be sum- 
marized as a loss of self-control and consequent 
change of character. In spite of these defects, 
the author’s statement of the subject of locali- 
zation is the best that can be found outside of 
physiological text-books. 
In an interesting chapter upon the compari- 
son of structure and functions of the brains of 
various animals, the conclusion is reached that 
mental activity is not proportionate to com- 
plexity of brain-development. He says, ‘‘ The 
state of the case is this: the dog, with a brain 
less elaborate in its convolutions, shows a 
higher degree of intelligence; the horse, with 
amore ample and complicated series of fold- 
ings in the convolutions, shows less intelli- 
gence. Advance in intelligence, and advance 
in complexity of brain-structure, do not keep 
pace with each other’’ (p. 148). He claims, 
on the other hand, that ‘‘ large development 
of brain, apart from marked development of 
sensory apparatus, is prominently connected 
with the functions of the motor side of the 
nerve system’’ (p. 259). These conclusions 
serve to introduce his theory of animal intelli- 
gence, which is the new feature of this edition. 
Animal intelligence, according to Dr. Calder- 
wood, is simply ‘ sensori-motor activity.’ It is 
reflex and automatic action. It is the same in 
kind, from the simple act of the mollusk in 
drawing in and expelling currents of water, up 
to many of the most highly complex and co- 
ordinated acts of man. The nerve system, in 
all cases, may be resolved into a typical form, 
consisting of two sets of fibres (one sensory, 
one motor) meeting in a central organ, which 
may be a single cell of the spinal cord, or a 
complex assemblage of bodies crowned by the 
cerebrum. Motion starting at the periphery, 
carried along the sensory nerve, is communi- 
cated to the nerve-centre, there modified, and 
thence transmitted along the motor fibres, out- 
ward ;to the muscle, where it produces motion. 
This is sensori-motor activity. It is discrimi- 
native and purposive. But from these charac- 
teristics it is a mistake to argue intelligence. 
‘** Purposive action nowhere necessarily involves 
intelligence ’’ (p. 205). The intelligence of 
animals, thus viewed, is the antithesis of intel- 
ligence in man, which has other characteristics. 
The degree of intelligence in animals depends 
upon the degree of perfection in their sensory 
organs. The great intelligence of the ant is 
due to its fine organ of touch, in the antennae ; 
that of the chick, to its power of vision; that 
of the dog, to its keen sense of smell, combined 
with its moderately developed sense of sight, 
etc. He concludes, that, in the whole range of 
SCIENCE. 
687 
animal life, power of discrimination is largely 
determined by the range of sensibility belong- 
ing to external organs of sense. ‘‘ The so- 
called intelligence of animals is nothing more 
than the purposive action of mechanical appa- 
ratus.’’? Their memory is mechanical, and 
does not imply true intelligence, as Huxley has 
long taught. The degree of intelligence in 
animals is due less to the development of inher- 
ent powers by natural selection than to their 
training by man. ‘‘ The intelligence of the 
dog is a distinct product of thousands of years 
of human training. Accordingly the 
intelligence of the dog is withdrawn from 
available evidence as to natural evolution of 
intelligence in the world. This is not 
intended as a denial of a law of evolution 
operating within living organism, but it mate- 
rially affects the structure of the theory of 
evolution by natural selection, taken as a 
whole’’ (pp. 250, 251). ‘* Evolution of or- 
ganism and of intelligence do not so harmonize 
that progress in the one can be a pure index 
to progress in the other’’ (p. 261). From 
the study of animal actions, Dr. Calderwood 
concludes that no animal interprets its own 
sensory experience, or develops its own na- 
ture, or improves that of its own species, by 
reflective exercise. ‘‘ All that is concerned 
with higher intelligence, whose natural function 
it is to seek the interpretation of sensory im- 
pressions, and to govern activity on principles 
of conduct superior to the impulses of sensory 
apparatus, lies quite beyond the region of in- 
vestigation hitherto explored. . . . Mind does 
not find a place within the area of nerve appa- 
ratus ’’ (p. 288). Mind is revealed to us by 
consciousness. ‘ Consciousness assures us of 
the existence of non-organic elements con- 
nected with sensory experience : viz., 1°, inter- 
pretation of impressions made on the sensory 
apparatus ; 2°, inference by comparison of past 
experience with present; 3°, synthesis of 
knowledge by use of forms and materials be- 
longing to mind itself. . . . These indicate 
the presence in human life of an intelligent 
nature distinct from organism, as it is different 
from that which we designate ‘ animal intelli- 
vemee-(p. 308). 
This view of the subject deserves considera- 
tion, however much we may differ from the 
author. Itis evident that Dr. Calderwood 
believes that there is no relation between brain 
and mind as he defines the latter. But being 
unable to ignore the resemblance between the 
intelligent action of animals and of man, or 
to pass by the many forms of interaction of 
mind and body as described in a subsequent 
