"through, the form of the meanest worm, then travels for a space beside the fish, then journeys along with the bird and the reptile for his fellow-travellers; and only at last, after a brief companionship with the highest of the four-footed and four-handed world, rises into the dignity of pure manhood." (Collected Essays, vol. xi., p. 5.)
Man and Anthropoid Apes.
I will not further speculate on the line of man's ascent, more than to say that among living animals, the orang, the chimpanzee, and the gorilla are the nearest to him both in somatic structure and mental endowments. It would, however, be contrary to all the known facts of evolution to suppose that man has sprung from any of these animals. But, on the other hand, there can be little doubt that, were we able to trace his pedigree far back enough, we would encounter a species which was a common ancestor to him and one or more of the anthropoid apes. But although we are not direct descendants of them, it cannot be denied that they are our first cousins. The morphological difference between man and his nearest of kin is comparatively small; but yet his mental capacity is so far above all other animals now living that many thoughtful men deny the possibility of bridging over the gap by any biological phenomena whatever. On this question the late Dr Allen Thomson, in a lecture delivered in the City Hall, Glasgow, in February 1877, expressed himself as follows:—
"I by no means wish to be understood to contend that our knowledge, either by nervous phenomena or of the structure of nervous organs, is yet such as to warrant dogmatic assertion of an indissoluble and direct relation between organisation and mind; but I venture to affirm that, if we deal with this problem in the same manner as with other scientific investigations, we cannot arrive at any other conclusion than that mental processes, however complicated they become in their higher forms, have taken their first origin in nervous action resulting from the vital activity of nervous structure, and that their rise into higher and higher forms of psychical phenomena is only a fuller development and closer combination of repeated and more complicated nervous action. . . . We do not know nerve force as distinct from the nervous fibre. We have good reason to believe that by some modification of that force in its passage through the nerve-cell, an afferent nervous impression is converted into an efferent impulse in the phenomena of reflex action. And it does no violence to our power of conception to extend the same view to the more complex mechanism situated within the cerebral ganglia, by which all these motions which we style automatic appear to be regulated without the co-operation or control of will or intelligence. When, however, the same afferent impression, which causes a simple reflex or a more complicated automatic motion, reaches the higher part
