1008 The American Naturalist. [November, 
sess this capacity, but it is quite possible that some low types of 
men rarely or never practice it. This we may derive from their 
vocabularies, from which words expressive of introspective mental 
_ states are absent. 
Consciousness of one’s body and of one’s mental sensations is 
no doubt present in animals. This is, however, simple conscious- 
ness, and not self-consciousness. Animals also possess con- 
sciousness of the mental states of other animals and of men. 
This is an inference based on their appearance, gestures, tones, 
etc, and one more evidence that many animals possess the 
rational faculty of induction or inference. 
4. THE METHOD OF MENTAL EVOLUTION. 
That the highest type of mind, as seen in mankind, has been 
produced by a process of evolution by descent from primitive 
beginnings would seem to follow from the history of the organ- 
ism which displays it, że., the nervous system and its ganglia. 
Whether there is any insurmountable obstacle in the way of 
such a belief will be considered in the present section. 
We have traced the existence of various component elements 
of mind among the lower animals, and have found that the only 
quality which is not common to them and to man is that of self- 
consciousness. And of this there is doubt as to its existence in 
the lowest human races. We have, however, recognized that the 
animal mind cannot reach so high a grade of conception in the 
classification of the mental contents, as can man. But we have 
seen how very greatly human minds differ in this respect, so that 
there may be said to be a rising scale of mental organism from 
the lowest animal to the highest man, with but a slight interrup- 
tion at the point where we pass from the highest ape to the lowest 
man. This slight interruption is due to the advent of language, 
which gave the mind a new machine, by which its power of ac- 
cumulating experience was increased, and a firm hold over its 
conceptual faculty acquired. The very inferior quality of the 
minds of the lowest races, however, leads us to infer the former 
existence of still less intelligent men, and their extremely simple 
languages lead us to suspect that the time was when man devel- 
