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for transmitting an influence through the same length of nerve without interruption. When the stimulus is weak, o proportionately longer time is required to produce the corresponding movement. We may hence infer that what is called nervous excitement is a quicker rate of the nervous current. The obvious facts bear out this view."

These then are the means by which an external force is received, modified and distributed in centres; by which an internal state directs and secures the succeeding steps in vital movement; by which an inner impulse of the mind is made in muscular effort to reach the external world; or by which these vital and mental forms of effort are inseparably blended.

Lesson 93 - 4. Cerebrum in man - p.387

4. The superiority of the Vertebrates in the animal kingdom is indicated by the presence and growing power of the cerebrum, the organ of conscious action; and the predominance of the voluntary life in man is disclosed at the same point. The supreme relation of the cerebrum in man to the other ganglia is seen in its absolute size, its relative size, its increase in relative size through all the grades of animal intelligence; in the number and depth of its corrugations, and the amount of blood it receives. Starting down no lower than the cod, we find the cerebral lobes smaller than the optic ganglia, and on a par with the olfactory ganglia. As we pass up they increase in absolute or in relative size, or in both, till, in man, they have stretched over and covered all the associated ganglia, multiplied manifold their relative dimensions, relative in reference to other ganglia, and in reference to the size of the body and become truly the superincumbent, overshadowing hemispheres of thought.

It is, however, in the combination of relations that man's great superiority is found, and not in any one of them alone. In absolute weight of brain he is surpassed