render it possible for true and safe localisation to be carried out. The study of the reflection functions of the cord assist materially in this direction. It is impossible to describe reflex action in this place, and indeed a full comprehension of this subject necessitates so much technical discussion that, even if space would permit, it would be unadvisable to weary the lay reader therewith. Suffice it to mention that, piecing together the work of the anatomist with that of the physiologist and subjecting the various theories to searching criticism, a doctrine of reflex action has been evolved, and this doctrine satisfies those who are in a position to judge it and explains the phenomena which clinicians have observed. Special mention of the experiments of Hughlings Jackson must be made in connexion with the levels of the spinal cord. Until quite recently, opinions differed considerably as to the correspondence of certain areas of skin and the segments of spinal cord which receive the nerves from the former and send nerves to it. Closely connected with reflex are the phenomena of inhibition and acceleration or facilitation. By this is meant that as the different parts of the cord and of the whole nervous system are associated with one another, one part or reflex arc may act on a second arc, inhibiting or putting a brake on the reflex action, or conversely may favour a fuller action, which is spoken of by the Germans as 'Bahnung.' Exner demonstrated this phenomenon by means of experimentation. An example of inhibition may be cited. The vagus nerve, which has its origin in the medulla, controls the action of the heart. A heart removed from the body continued to beat in response to the nervous mechanism contained within itself. If the heart is left in the living body and the vagus nerves on both sides are divided, the brake on the heart's contractions is removed; the heart beats without its controlling regulation, in a stormy, irregular and often rapid manner.

Apart from the supply of reflex action and the service of conductor, the spinal cord performs special offices in regulating, by means of ganglion cells, the functions of various organs. These functions are spoken of as visceral reflexes. The heart has already been mentioned. The lungs, the stomach and intestines, the gall bladder, the liver, the kidneys and tubes leading therefrom, the bladder, the prostate and the genital organs, all have special mechanisms in the cord. Golz, Ewald and various workers in Pflüger's laboratory discovered these reflexes, and the name of Head must also be included in the list. The importance of such functions of the spinal cord to practical medicine is not far to seek. A person has an affection of the spinal cord. The bladder reflex is affected by inclusion of the level in the diseased part. This symptom would therefore point to disease of that part of

the cord-namely, the lumbar, where the highest point of the bladder reflex arc is situated, and signs of further implication of this part of the cord would then be sought in order to confirm the diagnosis. The physiologists have in fact given the practical clinician guiding lines to enable him to distinguish between the cutting off of paths above certain centres and the implication of the centre itself. To conclude this part of the history of nervous research, mention must be made of the discovery of the functions of the spinal cord in preserving the tone and nutrition of muscles and other tissues. The experiments which played an important part in this direction were conducted by Golz and Ewald, and by Majendie.

THE NERVES

It would be an interesting task to trace the collection of fragments of knowledge concerning the spinal, sympathetic and cranial nerves, but only a short space can here be allotted to them. As has been mentioned, nerves are organs of conduction. They may not be regarded as mere lifeless wires which join up the delicate central portions of the nervous system with the muscles, skin, and other organs and tissues. Anatomy can only reveal the continuity of the nerve path, but physiology has, by means of elaborate experiment, revealed the living factor of the nerve path and the colossal difference between a wire and a nerve. Pflüger, Bernstein, Hering, and many others, have demonstrated the phenomena of the excitatory state of nerves. Nerves are permanently in a condition of excitability, and perform their conducting functions properly when their tension is maintained at a suitable height. Nerves feed, just as other living tissue feeds, and the nature of the so-called metabolism, or exchange of waste products for food products, has been minutely studied. The nature of the conductor has to be accurately recognised before it is possible to realise disturbances of conductivity. For this and many other reasons the physiological study of the nerves must be regarded as highly important for an accurate knowledge of disturbed conditions of the various parts of the nervous system; and a vast amount of useful knowledge has been gathered by means of animal experiment.

II

THE APPLICATION OF PHYSIOLOGICAL KNOWLEDGE TO CLINICAL PRACTICE

In order to place before the reader an approximate survey of the results obtained through the knowledge delivered by the

physiologist, it will be convenient first to deal briefly with those forms of disease of the nervous system which the physician, in contradistinction to the surgeon, still claims as his sphere. Many of these diseases are still incurable, and, though future research may be expected to throw more light upon them, since fresh methods are constantly being added to the existing ones, yet their treatment must of necessity remain but tentative, empirical, and haphazard until their true causation has been revealed. It is important, however, that the physician should be able to recognise a disease when he is faced with an example of it, and this can only be done if he possesses the knowledge of the normal tissues affected and the effect of disturbances of different kinds of the various portions of the organs or tissues. A correct diagnosis is always valuable to the patient. An example will show the truth of this statement. A person consults a physician on account of paralysis. The legs are affected more than the arms, the onset was sudden, and was associated with what the patient regarded as a cold; the general physical functions are normal. So far the physician in the old days would have been satisfied with the diagnosis of paralysis, and would have formed his opinion of the chances of recovery from the general condition of the patient. The modern physician, on the other hand, would seek for further information by testing the various reflexes, and, finding certain of these to be absent, would be in a position definitely to diagnose an affection of the nerves, called peripheral neuritis, and to inform the patient that he will recover within the course of a few weeks or months. This know

ledge is necessary for the breadwinner to make provision for his family. With a correct diagnosis the physician is enabled to apply the successful treatment, avoiding a treatment which, though proper for other conditions presenting many similar symptoms, but proceeding from different origins, would be ineffectual in the particular case. And even when the diagnosis reveals the existence of a necessarily fatal disease, much mental suffering, and bodily suffering also, may be saved by timely knowledge of the fact and by the consequent adoption of palliative

measures.

Fortunately, the physician has been able to benefit as well as the surgeon by the researches of the physiologist. For example, a patient complains of all the symptoms of, let us say, spinal paralysis. She is getting rapidly worse, and is weak and thin. The friends are terribly alarmed. Careful examination reveals signs which point to a functional disturbance, and not an organic one. The diagnosis is difficult, but it is possible when the physician knows what the physiologist has to teach. A rest cure and other treatment suitable to such functional disturbance

are adopted, and the patient is restored to health. It would be easy to multiply examples of the benefit which the physician has derived from the research work on the nervous system, until a whole book were filled, but the foregoing will suffice to show that, even when it is least expected, benefit from abstract knowledge reveals itself in the most practical form.

THE SURGERY OF THE BRAIN

Modern brain surgery claims a pedestal for itself. Its achievements have been great and unexpected. Its growth has been sudden, and for this reason its results are the more striking. In August 1888, W. Macewan wrote as follows: There were two formidable barriers to the advance of surgery in this region : First, the fact that the majority of intracranial operations were attended by inflammatory reaction, which so often proved fatal as to cause surgeons to shun active interference; and, second, the brain was a dark continent, in which they could discern neither path nor guide capable of leading them to a particular diseased area, and, did they attempt to reach it, it could only be by groping in the dark.' Antisepsis, which owes its existence to Lord Lister and to animal experiment, removed the first barrier. Much ado is often made between antisepsis and asepsis. It is glibly insisted that antisepsis is old-fashioned and has been cast aside in favour of the true prophet asepsis. But after all asepsis is an unattainable ideal. Septic microbes abound in the environments of life, and for the purposes of an operation must be destroyed. It is not asepsis to kill germs by boiling; heat is an antiseptic as well as carbolic acid. The means of killing germs have been altered since Lord Lister first taught that the germs had to be killed, but the lesson still holds good. and is the foundation of modern surgery.

The second barrier, ignorance of the seat of disease, has been removed by the experiments briefly touched upon in the preceding pages, and the patient research of the physiologist in accurately and minutely determining the centres in the brain for each tiny flexion of finger, deviation of tongue, movement of eye, &c., has guided the surgeon to the precise spot in the brain where his objective lies, and has given him the power to strike at a foe, which hitherto, within the known history of the human race, has absolutely defied all attack.

In order to give a general idea of the scope of modern brain surgery, it may perhaps be advisable to mention some of the diseases which have been dealt with in this way. These diseases naturally fall into one or other of the following groups-viz. : (1) Inflammatory; (2) malignant; and (3) infective. The nature

of the organ is such that any growth involving the brain must be highly dangerous, and if left untouched inevitably must lead to a fatal termination. In all diseases of the brain which come within the scope of surgery, a correct diagnosis is of the utmost importance. In many cases, however, many centres are affected, and the symptoms on which the diagnosis has to be made are manifold and complex. Without the knowledge gained by these experimental researches it would obviously be quite impossible to determine which parts of the brain are implicated in the damage or disease, and unless a clear and concise diagnosis can be made, successful operation must remain out of the question.

A minute description of the methods of diagnosis does not find a proper place in an article intended for non-medical readers, and a superficial one would tend to mislead. It is sufficient to state that the whole procedure depends upon the localisation of function, which has been briefly dealt with in the preceding pages. The extent of the diseased or damaged area and its origin can be determined by considering each symptom in connexion with the others, and by analysing the various disturbances of the voluntary and reflex movements. The following are a few instances of the type of case which presents itself for surgical help.

Case 1. The patient, a young man, was suffering from paralysis of one side of the body, and when admitted into hospital had been unconscious for twelve hours. A great membranous mass was discovered on opening the covering of the brain in the spot diagnosed. This mass was extirpated. In eight days the wound healed, and in six weeks the patient had recovered completely.

Case II.-This was another case of paralysis, affecting the left side of the body, in a young woman. The lesion was localised to a definite point in the brain, and an operation, which was performed through a trephine opening in the skull of the size of one square inch, for the removal of the disease was performed. In eight weeks the patient regained the power of movement, and complete recovery ensued.

Case III-A young man consulted the surgeon on account of epileptiform convulsions which occurred every five minutes, and of weakness of the arm. The diagnosis having been made, a cyst the size of a filbert was found in the brain and was extirpated. The patient made a rapid recovery, and the lost power was restored.

Case IV. The patient, a young man, was suffering from melancholy and agonising headache; he was able to see but was unable to understand what he saw. The diagnosis of a lesion in a certain situation of the brain, called the angular gyrus,

was made. The cause of the condition was found at the point