as well as in the limbic lobe, but the effects of a positive or irritative lesion have yet to be described, and, as will now be seen, give the final confirmation as a crucial experiment in truth ought to do. B. Effects of an Irritative Lesion (e.g. a small tumour) situated in a restricted part of the arm area, involving (but not destroying) the focus for the thumb.

(1) Tingling sensation in the thumb, which may be so marked as to amount to discomfort or even pain.

(2) Passage of such sensation from the distal (terminal) segment of the thumb upwards towards the wrist, elbow and shoulder, &c.

(3) Sensation as though the thumb were moved without any such motion actually occurring (a condition less frequent than (2), but most important).

(4) Movement of thumb (spasm or convulsion).

Of these phenomena the first two have been recorded by many observers since Hughlings Jackson more especially drew attention to them thirty years ago, and they constitute what is termed the aura or group of preliminary feelings in an epileptic fit. Those who hold the separatist view suggest that these sensations find origin in the perceptive centres in the limbic lobe which are secondarily excited by the lesion. Apart from other obvious considerations it would under these circumstances be difficult to imagine why such a waste of energy as this would involve should have been conceived to occur. The fact of this series of phenomena being evoked by a small localised and restricted lesion in the Rolandic region is in itself an unanswerable argument in favour of their development at the seat of the mischief.

But positive evidence answering the objection, though not absolutely or finally, is now to hand, since I have found that excision of the localised irritative lesion arrests these positive sensations and produces the anaesthetic condition.

On comparing together now the effects wrought by a negative or paralysing lesion with those evoked by a positive or irritative lesion in the so-called motor region, we see how exactly the one corroborates the other, with almost mathematical similitude and accuracy.

The conclusion is inevitable, that while no doubt the limbic lobe is the chief receiving station of sensory, tactile, and like impressions in general, the Rolandic or so-called motor region of the cortex is the position of an array of kinæsthetic or sensori-motor centres in which segmental sensory impressions, including what is in popular language termed the muscular sense, are represented and where "voluntary' movements find their source. Further, that a voluntary' movement in its most complete form or development includes, first, sensory perception in the limbic lobe or elsewhere; next, an intellectual process the localisation of which is unknown; and, lastly, VOL. XXIX.-No. 172.

3 N

an idea or concept of the movement to be performed, including the amount of force required for its production, this last being localiɛed in the so-called motor region, or more properly the kinesthetic centres, whence issues the output of nerve-energy which causes the muscles to contract, and in consequence is truly termed the efferent or motor impulse.

Now comes before us at once a most tempting point for discus-sion. Given that the cortex of the Rolandic region is kinæsthetic, from which element of it does the efferent impulse start, and where are localised the muscular-sense' impressions?

The microscopical anatomy of this part of the cortex is fairly well known. A thin section of it suitably prepared shows that the nerve-corpuscles (or cells) are arranged in five tiers one above another, and that while the vast majority of the corpuscles are small, those in the fourth tier have interspersed among them some striking large corpuscles. Reasoning by analogy from the structural arrangement and size of the nerve-corpuscles in the simplest nerve-centres of the spinal cord, it may be justifiable to regard the large corpuscles as mainly efferent in function, and as, in fact, the last cerebral station from which the volitional' impulse starts on its way down the fibres of the pyramidal tract in the spinal cord to ultimately reach the muscles by way of the motor nerves. If this reasoning is justifiable and it is supported by the authority of Dr. Ross-then is it as proper to regard the small corpuscles as possessing afferent function or mainly sensory representation, such as that the nature of which we have seen emphasised by the effects of lesions, namely, a slight degree of tactile æsthesia, a topographical localisation of the same according to the segments of the limbs or body, and a complex æsthesia of the position of such segments in space, this latter being a compound of the impressions received from the muscles, fasciæ, joints, &c.

Let me, in summing up, illustrate my line of argument by detailing the answers made by one of the cases on which this paper is based. It was the condition in this instance, viz. a lesion in the thumb area, which I chose as my typical example, because naturally the specialisation, or, in other words, the high cortical evolution, of the representation of the thumb made it so salient a subject that the points it exhibits could be easily grasped.

The disease, a tumour, affected in the right half of the brain the 'centre' for the thumb according to Beevor and myself. After the removal of the growth the surrounding part of the brain was temporarily disabled by shock. As it was recovering, being hyperexcitable, the patient experienced for several days some painful sensations in the left 13 thumb and hand. On saying to

13 Left, of course, because the right half of the brain corresponds with the left half of the body.

him, 'Whereabouts in the hand do you feel the painful sensations?' his reply was, 'Inside, in the bones,' 14 thus indicating that the sensory impressions were those of the muscles, joints, bones, &c., the summation of which in excess constituted his discomfort or pain. But the most striking fact was the following reply to the next question. On saying to him, 'What becomes of the pain-does it stop in the hand?' he replied, 'No, it goes up the arm and neck to the head;' and, suiting the action to the word, he drew his sound right hand up the back of the left paralysed one, up the arm and left side of the neck, finally placing his forefinger exactly upon the seat of the lesion in the right Rolandic or so-called motor region. Considering that the patient was an agricultural labourer of very limited knowledge, this unexpected demonstration by him of the doctrine that the centres in the Rolandic region are indeed kinæsthetic was startling and, I may add, a revelation.

In conclusion I may be allowed to justify what must appear to many the establishment of but a small point, but which is in reality a very important one. Our knowledge of the physiological process underlying a voluntary act was practically nil until the experiments of Hitzig and Fritsch and Ferrier in 1870, and since that epoch when the localisation of the motor or efferent apparatus of the nervous system was shifted at a bound, as it were, from the base of the brain to its surface, we had not until a few years ago advanced much further in the neurological analysis of a voluntary impulse. That analysis as planned by Bastian has resulted in the determination of another stage towards the mental aspect of the phenomenon in question. His interpretation shows clearly the close connection between the sensations of tension and motion and the subsequently perfected development and execution of the movement desired, while it demonstrates what functional phenomenon immediately precedes the discharge of nerve-force, or, in other words, the voluntary impulse. This is the step in advance which has now been gained. Like all true advances in physical science, it harmonises and explains conditions which before were deemed perfectly incompatible and, in fact, incomprehensible.

If this much is achieved, I may in conclusion look forward to see in what direction to plant our next step.

The problem now remaining is, How can a way be forced through the yet impenetrable mist obscuring the field of the intellectual operation or central stage of a voluntary act? Of its physical substratum or basis we know nothing. Of the physical substratum of the psychic processes on each side we know something, since that of the one is a sensory perceptive centre, and that of the other a kinæsthetic centre. In trying to solve this difficulty we naturally

14 This answer I have frequently received since, and it is remarkable, though of course most natural, how the mass of sensory impressions under these circumstances, viz. of lesion in the Rolandic region, relate to the deep structures.

ask ourselves, Is there an intellectual centre which would form the physical substratum of the mental faculty of reason?

It is fairer, perhaps, to ask at the same time why should there be such a centre? Of the actual mode of connection between the mental process of a conceptual ideation of a voluntary movement and the physiological or functional activity of a kinæsthetic centre we know nothing, though of their parallel existence, if not identity, we feel certain. It is not, therefore, unreasonable to indulge our imaginations in the thought that the highest, i.e. most complex and extensive, regions of the perceptive centres may be the place wherein to search for the physical basis of intelligent reason and deliberation, which last for so long delusively offered an easy test of volition. To analyse more deeply the depths of sensory perception, therefore, must be the future task of the neurologist. With this goal in view we must leave the subject, satisfied with the feeling that our knowledge of the process of volition is becoming surer more rapidly now than at any previous period in psychology.

VICTOR HORSLEY.

A DESCRIPTION OF MANIPUR.

It is scarcely two months since all India and England were startled by the news of a great disaster in Manipur, and the cry instantly arose, "Where is Manipur?' most people in India being quite as ignorant of its whereabouts as the inhabitants of the United Kingdom, the general idea being, among those who had heard of it at all, that it was in some way connected with the game of Polo. Yet Manipur is a country with many features of great interest, it contains scenery of surpassing beauty, every variety of climate from an almost tropical one to one colder than that of England, finally it is the home of an intelligent race of people quite distinct from any other Indian one, and with a history and civilisation of its own well worth a little study. The valley of Manipur, the heart of the country and the only part where the pure Manipuris live, is an open plain 650 square miles in extent, and of irregular shape, its extreme length from north to south being, perhaps, thirty-five miles, and its breadth from east to west twenty-five. With exception of the villages, which are well planted, and a few sacred groves here and there left for the benefit of the sylvan gods, the country is devoid of timber. The capital, called Imphal, is a large mass of villages and from the neighbouring heights presents the appearance of a forest; it covers a space of about fifteen square miles. Every house in the capital is in its own wellplanted garden, hence the large space covered; the population at the census of 1881 showed it to contain 60,000 inhabitants; the remainder of the valley had another 60,000; while the hill-tracts accounted for 100,000-making in all a population of 220,000, the extent of the little state, hill and plain together, being 8,000 square miles, or a little larger than Wales.

The valley itself is 2,600 feet above the sea-level and is completely surrounded by hills of an average height of 2,500 feet above it; the sides of the hills facing towards the valley are generally grassy slopes or at most covered with scrub jungle, but as soon as the crest is passed a fine forest is reached, except where the hill-tribes have ruthlessly destroyed it to raise one crop and then let it relapse into grass or scrub. But we must briefly describe the situation, and say that the valley of Manipur is east of Cachar and west of the Kubo