These lines, as electricians say, complete a circuit. Suppose, for example, a needle-point enters my finger. The sensitive impulse goes by the fibers of the afferent strand to the central cells in the spinal cord. From the central cells a motor impulse is returned by the efferent branch to the arm, hand, and finger, to withdraw from the offending body. The point of departure of the sensitive impulse is the terminal point of motor energy, and the circuit is complete. It is possible, too, that the hand may be withdrawn as soon as or even before I am conscious of pain. How is this?

It is thought that only the cranial nerves have an immediate, direct connection with the brain; that sensations going by way of the cord advance by relays, as it were. That is, the sensitive dispatch is first received by the central cells in the gray matter of the cord, and by these re-transmitted along the lateral or posterior columns to the centers of consciousness. But while the re-transmitted message is going upward, the motor impulse has already gone outward to withdraw the member. By thus taking the matter in hand, the spinal cells save time, and even the thousandth part of a second is valuable where a hand is in the fire. If deliverance always had to wait for the longer circuit of consciousness and will, the amount of injury might be greatly increased.

Co-ordination Of Voluntary Muscular Movement.

This is certainly one, if not the only, office of the gray matter of the cerebellum.

This co-ordination is one of the most wonderful results of life which our eyes behold. It begins to be manifested before birth. Then, as we watch the movements of an infant newly born, we observe that while these are weak and awkward, there is something of regularity and correspondence, showing that the organs have taken their first lessons. Day after day witnesses an increase of nervous rhythm and muscular agreement. As the child grows the co-ordinating powers are educated. When he first wills to walk, he falls. It is only after many trials and repeated failures that he is able to maintain a position of equilibrium above his feet. ,

Think what a difference there is between such manifestations and those of the acrobat or bare-back rider in Barnum's circus. What a difference even between the movements of the ordinary pedestrian and the first attempts of his babyhood.

Listen to the ceaseless tread of the great human army marching to and fro upon our streets; watch the daily panorama of complex activities that moves before your eyes. Stand and wonder and admire the strength and the precision, the grace and the beauty of movement, that join and flow together from the fountains of co-ordination!

But the chief glory of the human organism is not found till we climb beyond nerve and cord, medulla and cerebullum, to the gray matter of the cerebral convolutions. Here dwells the king. Here in this mysterious chamber are wrought the still but mighty works of intellect, affection, and will.

Other animals may be immeasurably superior to man in bone and muscle, equal or superior in certain co-ordinations; may have finer organs of special sense; but in the one thing of cerebral gray matter, the organ of thought and reverence and benevolence and will, he stands alone upon the earth, having "dominion over all."

Underlying Principles Op Manifestations Of Nervous Energy.

I presume we have all of us often asked ourselves, What is the underlying principle of this transmission of nervous energy, motion, or sensation? What is it that travels along the nerve? Does anything really travel? We have heard of ethereal fluid, nervous fluid, electrical fluid,—an intangible, indefinable something supposed to whirl along the nervous lines like a cash-ball on the track in a modern retail store. Is there any such thing? I take it that all these operations proceed on the principle of contact. It is entirely a matter of touch.

The sensitive cell is simply the ultimate cell exteriorly of a series of cells. It is the extreme end of a nerve-filament. The first cell being touched, touches the second, the second the third, the third the fourth, and so on till the central cell is reached. What matters it that all is done in an inconceivably short space of time? It is touch, vibration, modified tension,—as you please to name it.

Suppose you could have a man stand out before you, and then, by a word, annihilate or throw off absolutely everything of him except his nervous system. What would he look like? Why, the form of the whole man would be there, less hair and nails. He would be a very nervous man, to be sure, but he would demonstrate most clearly the perfect diffusion yet unity of nerve-tissue. You might be able to see that the nerve-filaments are but fingers, millions of microscopic fingers, reaching out to touch the things in which the brain and cord have an interest. Touch the periphery anywhere, and you touch the center. It is all on the principle of contact of atoms and the communion of matter.

Our knowledge of the telephone may perhaps be made to assist in making the idea more clear to our minds. The construction of the telephone is simply this: Two vibratory membranes are connected by a wire. So we have in contact—air, membrane, wire, membrane, air. The man at one end sets the air in motion, producing sounds with his vocal organs, varying in intensity and number so as to constitute what we call speech. The man touches the air, the air the membrane, the membrane the wire, the wire the membrane, and this again the air; and the air touches the other man,— his ear. So by these media the two men touch each other. The one makes impression upon the other by certain nicely adjusted movements which he has been educated to make. The other understands the movements because he has been similarly educated both to make and to perceive. It is a mode of motion.

Again, here are two telegraph operators,—one in Chicago, the other in New York. A wire connects their offices and certain cups or jars. In"these jars are certain chemicals which produce atomic disturbances of a definite sort. The communication of this disturbance to the atoms of the wire is under the control of the operator. He can continue or break it at will by means of his finger on a key or button. By training, he has learned to break with varying intervals,—short breaks, long breaks, combination of breaks, so as to make an alphabet and spell words. In so doing he is playing on all the atoms of the wire, and by them the breaks or sounds are registered or reproduced at the other end, and understood by the other man. Now, the man may do all this without understanding the process at all, aside from certain mechanical executions, just as men have been talking for ages without knowing they had vocal cords. But you see that the telegraph, as well as the telephone, is simply a practical use of one of the modes of motion, and an adaptation of the principle that atoms everywhere touch.

The world is under tremendous pressure. There is tension everywhere. Every object in some way, directly or indirectly, touches every other ""object. But by the isolation of certain lines of atoms, as in the telephone and telegraph wires, we are able to control and utilize the sensitiveness of matter in a definite way, and for a definite purpose.

So our nerves are merely isolated lines of atoms. The terminal sensitive cell touches the central, and the central in turn touches the lines of atoms that provoke contractile energy. And so we have sensation; and so we have motion.

-f THE TEEATMENT OF DEEP-SEATED ABSCESSES WITHOUT EXTEENAL INCISION.

BY JOHN S. MARSHALL, M.D., CHICAGO, ILL.

[Read before the Minnesota Dental Society, August 1, 1885.]

By deep-seated abscesses I mean those cases of alveolar abscess which have extended beyond the ordinary limits, and have involved more or less extensively the structures of the jaw, with a tendency

to necrosis, or have penetrated the antrum of Highmore or escaped from the neighborhood of the maxilla, and have burrowed downwards between the muscles of the neck, as frequently occurs in abscesses associated with the inferior teeth.

Ordinarily the diagnosis of these cases is not.difficult, but occasionally the cause has proved troublesome to find. Abscesses discharging into the antrum, or the nasal fossa, and producing offensive discharges, have been diagnosed as chronic catarrh. One case occurring in the practice of Dr. Edward Maynard, of Washington, D. C, caused by an unerupted inferior wisdom tooth, and discharging into the larynx, setting up an irritative cough with expectoration of pus and mucus, was previously diagnosed by the physicians to be acute bronchitis; others discharging at some point upon the side of the neck have been set down as abscesses originating in the cervical glands, the result of scrofula.

That such abscesses often prove to be serious affections, endangering the health, and sometimes even the life, of the individual, are well-established facts.

I purpose, however, in this short paper to confine my remarks to the more common, and, from their location, the more dangerous class of these cases, viz., those originating from disease of the inferior teeth.

The tendency of the suppurative products in these cases is downwards through the external wall of the alveolar process, and to point at the lower margin of the jaw; but it also happens—especially with the molars—that instead of pointing at this location it opens through the internal wall of the alveolar process, and burrows downwards between the muscles of the neck, and may discharge into the throat, or through the external tissues at various points from the submaxillary triangle to the superior border of the clavicle. Any suggestions, therefore, in regard to the treatment of these cases which will tend to cut short the suppurative process, lessen the dangers to health and life, avoid the necessity of operating with the scalpel in a location requiring such delicate dissections and fraught with so much risk to the patient, or to prevent the unsightly and ofttimes disgusting scars which follow the external opening of these abscesses, will I think be of interest. The treatment frequently adopted in cases of alveolar abscess is the removal of the cause by the extraction of the offending tooth, trusting to nature to complete the cure.

In extreme cases of this deep-seated variety an incision is made through the external tissues at the lowest point of the abscess, for the purpose of drainage. In those cases, however, where the pus has burrowed deeply-into the tissues of the neck it is quite likely that more than one pocket will be formed; consequently the treatment by incision becomes complicated, and sometimes, from the dangers of an extended operation in the superior or inferior carotid triangles, would be precluded altogether.

The surgeon, under such circumstances, has had no alternative but to wait, trusting that the abscess would find an opening for itself at less risk, before the patient should die of pyaemia. The treatment which is suggested comes to our relief in this emergency, and from past experience I am prepared to say, at least, that the duration of these cases can be materially shortened, and many of them speedily cured, without resort to any other operative procedure than the extraction of the diseased tooth and the injection of peroxide of hydrogen into the sac.

Ophthalmologists and aurists have found this agent very useful in the treatment of diseases of the eye and ear, with purulent and muco-purulent discharges, and dentists have been signally successful with it in the treatment of pulp-chambers with putrid contents, in ordinary alveolar abscesses and in pyorrhea alveolaris. By injecting an abscess of the deep-seated variety with peroxide of hydrogen, introduced through the alveolus of the extracted tooth, the purulent contents can be thoroughly evacuated.

The oxygen is set free on coming in contact with the products of decomposition, which distends the cavity and forces out the pus through the alveolus by mechanical pressure. Two or three injections of from a half drachm to an ounce, according to the extent of the abscess, may be required to completely remove the purulent matter, and if given opportunity it will search out and purify every hidden receptacle. I have had several opportunities since its introduction to the notice of the dental profession, by Dr. Walter Coffin, of England, at the London International Medical Congress in 1881,* to test its efficiency in this class of cases, and in extensive periosteal inflammations of the jaws.

In one case, a Mercy Hospital patient, Mary N"., Irish, aged twentyfour years, was suffering from a deep-seated abscess associated with the right inferior wisdom tooth for several weeks. The patient was confined to her bed for twenty-six days, with pulse ranging from 100 to 116, and temperature from 101° to 104.8°. She was speedily relieved by extracting the tooth and evacuating the pus. The abscess extended down the neck four and a half inches below the margin of the gums, as was ascertained by the probe. The pulse dropped from 104 to 96 and the temperature from 104.8° to 103° within two hours after the operation. A half ounce of the peroxide

* Transactions of the Seventh International Medical Congress.