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194 as a whole. It is impossible to discourse, with any degree of fulness, on this subject in the present course of lectures; but I shall content myself with alluding to one or two points of surpassing interest.

In the first place, these—the muscular mechanisms we have been considering—are controlled and regulated by the central nervous system. Each muscle is supplied by one or more nerves, and these originate in central nervous organs of great complexity, and regarding which much of our knowledge is singularly indefinite and unsatisfactory. We know, however, that there are two classes of movements—those that we make voluntarily and consciously, and those that we make involuntarily, and of which we may be either conscious or unconscious. We cannot make a voluntary movement without being conscious of so doing. An effort of will is always a conscious effort, and to speak of unconscious will, as some writers do, is, in my opinion, a very misleading mode of expression. What they mean, no doubt, is that certain movements may be made which are so purpose-like as to lead one to suppose that they are voluntary, and yet they