900 The American Naturalist. [October, 
In this chapter I will first compare the mental faculties of man 
and the animals below him, and will then consider their progres- 
sive evolution. , 
I. CONSCIOUSNESS. 
The faculties of perception or observation, form the primary 
division of mental processes, and the most simple. They include 
those of general sensation and of special sensation. To the latter 
belong smell, hearing, taste, and sight ; to the former, touch, tem- 
perature, muscular sense, etc. It may be inquired, What have 
these functions in common with the affections, the intelligence, and 
the will? They have the important characteristic in common, 
that they are all forms of consciousness, or self-knowledge. All of 
these functions are forms of consciousness, although some of the 
representative faculties may become automatic and unconscious after 
education. Consciousness, then, is the one common property of 
all mind; and, from the point of view of the evolutionist, progres- 
sive development of mind is the advance from the simpler to the 
more complex, or from the generalized to the specialized forms of 
consciousness. Mind, then, in this general sense, embraces every 
and all kinds of metaphysical condition, including the unconscious 
derivatives of conscious antecedents. Of this latter mental type 
more will be said later. | 
_ That many of the higher animals possess mental faculties which 
must be referred to the divisions of the intelligence and the affec- 
tions, is evident to every person who is familiar with the animals 
themselves. That the simpler affections or “ instincts " are present 
in animals very far down in the scale, is also obvious. That 
special senses exist in animals as low down as the Coelenterata 
has been shown by Dr. Romanes and Prof. Eimer. General sen- 
sation is probably present in still lower forms of life; but which of 
them possess this simplest form of consciousness, and which do not, 
is at present very difficult to state. We may, however, form an 
estimate of probabilities in the case by observing the movements 
of Protozoa under stimuli, as well as those of the spermatozoöids 
and phagocytes, which have a free existence within the bodies of 
all but the lower forms of life. 
