There can, perhaps, be no more pleasing conviction than that which assures a man he has won the approval of his fellows; and in gratefully acknowledging the great honour conferred upon me to-day in my election to the Presidential Chair this conviction is mine, and I take the award as an earnest of your good will and confidence. But, as in the richer harmonies of human life the minor chord will ever assert itself, so the knowledge of one's personal limitations introduces a note of sadness, for one is forced to recall how very little, even of one's best, one can give in return for so invaluable a pledge of the esteem of one's fellow-men.

Six years ago Dr. Shennan and I recorded the observations that rats which had been fed with cultures of a threading diphtheroid bacillus, isolated from the bronchus of a general paralytic, developed symptoms of paresis, which tended to go on to a fatal termination, and that the tissues of the animals showed changes resembling those that are found in cases of early general paralysis. In all of four animals in which the experiment was fully carried out the brain showed periarteritis, neuroglia proliferation and severe nerve-cell lesions. Two years ago Dr. McRae and I recorded some further experimental observations upon the effects of feeding rats with various strains of diphtheroid bacilli. A diphtheroid bacillus, which formed acid in glucose and saccharose test broths, and which was virulent to mice (Bacillus paralyticans brevis), produced very striking results in twelve animals. They developed acute or chronic forms of general paresis which went on to a fatal termination. The most marked lesions found after death were those affecting the nerve-cells of the spinal cord and brain, but in several of the animals there were also distinct periarteritis and neuroglia hypertrophy. Similar experiments with several other strains of diphtheroid bacilli, which could be classed as one or other of the two forms to which we have attached special importance, gave much less definite results. Some of the animals have not yet, however, been examined microscopically. Control animals fed with other organisms gave quite negative results. These experiments have at least shown that diphtheroid bacilli isolated from cases of general paralysis may occasionally have sufficient virulence to determine in rats, by infection through the alimentary tract, a disease in which the chief symptoms are those affecting the nervous system, and in which the tissue changes have a certain resemblance to those found in general paralysis.

This research was undertaken to establish, as far as possible, Drs. Ford Robertson's and McRae's ætiological hypothesis for general paralysis of the insane. It is hardly necessary to emphasise the importance of giving the fullest consideration to this theory, being, as it is, the first serious attempt of its kind to bring mental disturbance into the category of physical disease, to establish the wealth of histological observation in its place as an effect, and to break from the bugbear of metaphysics and perversion of psychic function. I should like to make it clear that though this research may controvert the ætiological significance of the bacilli of Ford Robertson, it in no wise attacks the fundamental theory of a toxic cause acting through the very definite channels of infection established by Drs. Orr and Rows.

I wish to lay before you the results of an examination of the cerebro-spinal fluid in general paralysis and the nervous lues compared with insanities of almost every type, with a few cases of organic disease other than brain disease, and with ten normal fluids. The most serious difficulty met with in obtaining fluid by lumbar puncture with a view to chemical analysis is the admixture of blood. I may mention that in no instance have I seen any ill-effects on a patient from the withdrawal of the fluid; nor have I noticed any abatement in the acute conditions of general paralysis. The investigation has included the detection of albumose, nucleo-protein, and cholin; the reactions, according to Wasserman, Noguchi, Porges-Meier, associated with syphilis; and an estimation of the cell content, specific gravity, and the reduction of Fehling solution.

Changes in the mental condition of the patient are frequently to be recognised as one of the earliest symptoms of exophthalmic goitre. These mental changes may be present before the cardiac or ocular symptoms have been established and before the changes in the thyroid have been observed. The most common feature is an intense and indefinable agitation leading to a more or less marked motor and mental restlessness, which causes the patient to look for constant change in her surroundings and work. There is an inability to settle long to any one occupation or recreation. Work begun with a feeling of relief at the change involved soon becomes irksome, is then done only with an effort, and with the cumulative feeling of effort and concentration required soon causes distress and the work is laid aside. Any sudden noise, any unexpected news, any of the ordinary disturbing elements of everyday life may be followed by an attack of palpitation lasting some hours, and yet, in spite of this, there is an imperative desire to keep moving; to go where such incidents may be experienced. Dr. Geo. Murray, in the Bradshaw Lecture of 1905, states that he has not noticed this craving for entertainment. It seems to be entirely a question of degree. If the stimulus is moderate there may be pleasure in its fulfilment; if more marked it may pass into an apprehensive dread with inhibition of this desire.

This paper is an answer to a challenge thrown down by Dr. Urquhart on the occasion of the Annual Meeting of this Association in 1905, when I had the honour of reading a short description of the small hospital we were then opening in Brighton and its raison d'être.

In confining the following remarks more particularly to a personal experience, I trust I shall not appear unconscious of the more able treatment the subjects of this paper have received at the hands of more experienced observers.

The subject of the experiences about to be described is a literary man of great ability and a recognised authority in a certain department of learning, who had unfortunately been addicted to the abuse of alcohol for many years and had decided to try the effects of a course of atropin treatment. He was perfectly sane. Previous to his admission he had been practically living on milk and whisky for a considerable time, taking five or six glasses of the latter in the day. The whisky was at once greatly reduced, though not altogether stopped; and combined injections of atropin and strychnine were begun on the day of his admission (November 22nd), with dietetic and other treatment, but no sleeping draught was given either that night or the next. This was the first case which I had treated by the atropin method, and I should not now commence the injections so soon after admission. No other case, of a good many since treated, has suffered from hallucinations, but they have often been met with by others.

It is indeed a true saying that to be successful in the treatment of disease clinical observation must be accompanied by biological and bio-chemical research. Yet the practice of medicine in times not so very remote was chiefly based on careful observation and common sense. In by far the majority of diseases the ætiology was not understood, and this was strikingly true of the acute forms of mental derangement. Still, devoted workers and searchers after truth continued their investigations on the dead and their experiments on the living. Gradually appliances were improved and new methods pursued, and with such brilliant results that at last the true cause of infective disease was discovered. One by one bacteria were isolated and studied, and thus a great world of medical research was opened out and results obtained which have already wrought untold blessings to humanity.