matter composing these keys has in it the power and potency of all music, from the simplest air up to Beethoven's Fifth Symphony. Let him go behind the organ, and elaborately study the very powerful and purely physical forces at work in the interior of the instrument. Let him show, learnedly and laboriously, that currents of air thrown into the pipes produce, according to merely mechanical principles, the wholly physical concussions in the molecular particles of the atmosphere which are concerned in the music. As no merely physical science, by any test known to man, can detect the presence of the musician, let this observer assert that there is no musician independent of the instrument, and that the anthem proceeds wholly from the mechanism of the organ, acted upon by exclusively physical stimulation from without. Let him assert that the hypothesis of an invisible musician is as absurd as the attribution of aquosity to water, or of horologity to a clock. According to this supposed materialistic observer of the organ, there is nothing in the anthem which is not wholly the result of the mechanism of the organ on the one hand, and of the merely physical forces supplied to it by the organ-bellows on the other. Let this naturalistic observer have a great name -- among men of his own opinions.

Should we be puzzled by these confident assertions? Not if we held fast to the Ariadne clew of the self-evident, axiomatic truth, that every change must have an adequate cause. We should say that this instrument, being made wholly of matter, is

inert. We should assert, in the name of established science, the incontrovertible inertness of all parts of the organ taken alone. We should say that the motion of rough currents of air through it does not and can not account for the intricate and ravishing melody which captivates our souls by its intelligence, and must have behind it a soul. Mere wood, metal, and ivory cannot utter Beethoven's spirit. Perhaps the air, by the slight pressure of intelligence on the keys, can be ruled into melody, and made to give all its majestic force to the intelligent weaving of the anthem. But in your organ, as elsewhere, involution and evolution are a fixed equation. You bring out of it only what you put in. Your musical instruments will throw no Beethoven into the air, unless there is a Beethoven at the keys.

Such, my friends, is the stern outline of the inef faceable contrast between the body and the soul. The distinction between matter and mind is a gulf as vast and impassable in physics as in metaphysics. The soul wears Gyges' ring. It is, indeed, invisible to the microscope, and intangible to the scalpel. But there are mysterious molecular motions in the nervous substance of the brain. Neural tremors fill the keyboard of the body. Undoubtedly there is a perfect correspondence between these tremors and the anthems of thought and emotion, in your Homer, your Demosthenes, your Cæsar, your Milton, your Shakspeare. But the parallelism is not identity. Motions and forces are not the same. The keys in motion are not the music. Physical forces play

through the brain; but they do not sing, unless modulated by the ineffable touches of the keys. Just as surely as you, from the structure of an organ, may infer the necessity of a wholly exterior agent to move it, so, from the structure of the nervous system, we must infer the necessity of a wholly external agent to set it in action. [Applause.]

In what I am about to put before you I have the authority of Frey, of Stricker, of Ranke, of Kölli ker, of Carpenter, of Beale, of Dalton, and of Draper.

1. In the nervous mechanism there are two kinds of fibres, called by physiologists the automatic arcs, and the influential arcs.

We have here a representation of the simplest kind of nervous fibre [illustrating by a figure upon the blackboard], - the pendent curve of a nervous thread, one end in contact with the external surface of the body, and the other connected with this muscular tissue. If you please, the bioplasts weave all that. Perfectly simple as the structure looks, it is a miracle. Can Can you make any thing like it? Here is your muscular fibre, which has the peculiar quality of contracting under nervous stimulus. Here is your nervous cord, which transmits strange influences that cause contraction when they are received upon this muscular tissue. One test by which true. is to be distinguished from false science is, that the former does, and that the latter does not, concern itself carefully with beginnings. Remember, that, even in this automatic nerve, motions and forces are

not the same. Muscular contraction is an effect of physical forces only as these act on mechanism arranged before the forces themselves came into play. Your miraculous brain is first woven by your bioplasts. You say mind is the result of the mechanism of the brain; but the mechanism of the brain is the direct product of bioplasmic action.

Of course, I am ready to admit, that, if you touch a portion of this automatic nervous arc with a galvanic current, you will produce contraction there in the attached muscle. Electrical stimulation of such a nerve may produce a contraction of the muscle even after the man is dead. But what wove that nerve? What wove that contractile tissue?

Beyond this simplest structure, the next higher in the development of the nervous system is what is called the cellated nervous arc. We see it here, a pendent curve as before; but now with a very large bead, or mass of nervous matter with bioplasts in the middle of it, is hanging at this point. It is yet true that irritation here produces contraction there. What influence, then, has this nervous centre upon the transmission of this nervous force? The books say that there is no proof that the nervous influence is changed in quality by its passage through one of these simplest ganglia. You may single out a nerve arc of that primitive style, and irritate it by an electric current on one side of this large bead or ganglion, and you will produce contraction in the muscle just as before. You irritate this side beyond the great bead, and you produce contraction.

But a third step in the development of the nervous system does introduce a change. Many of these nerve-centres are tied up to other nerve-centres [illustrating by a figure in which the ganglion of the nerve-arc was connected with another ganglion]; and in a nerve with its ganglion connected in that style with another ganglion, a portion of the influence transmitted through this complex nervous mass is thrown off into this other complex nervous mass. Your physiological authorities call the latter a registering ganglion. This transmission of nervous influence into the registering complex of nervous matter may be very inadequately illustrated, Professor Draper says, by a faucet with three stops (DRAPER, PROFESSOR J. W., Human Physiology, p. 380), or by a mirror with a portion of the isinglass taken off the back. The light is in part reflected and in part transmitted. Thus this registering mass of nervous matter retains a portion of the force sent through this nervous arc; and, in an animal possessing this nervous mechanism, there will be memory, or something equivalent to it.

Thus far we have seen only what is called the automatic nervous mechanism. Please fix in your minds, gentlemen, the simplicity of this structure, and, when a more complicated mechanism is outlined in connection with this, keep vividly before your minds the contrast between the two.

All established science is agreed that there are automatic and also influential arcs in the nervous system, and that the contrast between the two things is as marked as that between their accepted scientific

names.