6 animal, but he has the power of inhibition and of autocriticism, and through the influence of his environment he has attained a veneer of civilisation, and it is interesting to note that in insanity these acquisitions of his progress are gradually dissociated and shed in the inverse order of their acquirement, until at last man is left a wreck barely above the level of the animal. The cause of this reduction in insanity is probably some physical process in the cortical cells, or, in other

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... s, some chemical change has occurred in the neurones, either directly through the influence of some poison generated from within or introduced from without the body, or indirectly by means of the environment, favoured, of course, by some inherited predisposition ; and it is the study of man biologically--that is to say, the observation of his general activity or his total reaction under the influence of physical and psychological impressions-that enables us to infer the kind of temperament a man pos3eses. As we have seen, the predisposition to states of instability of control may be associated with distinguished mental superiority, and it is the degree of sensitivenei-s to pleasure and pain, the degree of motor restlessness and the degr e of emotional tone exhibited by the individual which justify us in concluding that there is or is not present a temperament which we are entitled to describe as the neurotic, and it is by foreseeing this temperament that we can promote happiness and harmony where otherwise there would be intolerance, strife, and discordance. The more we see of the deviations of mental reaction and of physical structures the more we must be convinced that special modes of nutrition must have their special phybiological expression, and that our work of prevention and relief as medical men is as important for the welfare of the community and the progress of the race as it must bettor the well-being of the individual. AN ABSTRACT OF LECTURE I. Delivered on May 15th. ANALYSIS AND DEFINITIONS. THE association of the medical science of climates with that of*baths and waters is not accidental, nor founded only upon a convenient grouping of two chief modes of physical therapeutics. It is a real and essential connexion, for whilst the influence of climates often operates alone it is inseparable from, the action of baths. In truth, the climatic factor enters into every balneological equation. At every spa the influence of the waters and baths and of the local climate are inextricably mingled. Whenever a patient is submitted to baths or waters the climatic factor is an accessory, and sometimes a dominant, influence. For this reason the study of medical climatology, b-)th in its general principles and in its local and special applications, can never be overlooked by the spa physician. The various spas, both British and foreign, enjoy a great variety of climates, and it would be possible, and indeed desirable, that they should be grouped according to their climatic characters. Many waters and baths, apart from the climate, produce, with minor individual differences, the same general effects. The climate is often, therefore, the determining factor in the choice of a particular spa for invalids-and in this matter the general condition and temperament of the individual must be considered as much as his malady. Moreover, an appropriate climate will reinforce the effect of the spa treatment, as an unsuitable one will antagonise it. This applies with especial force tc cardio-vascular and nervous disorders. A large number of patients so affected are benefited more than by any other form of treatment by subthermal baths, still or gaseous. Of these cases, some should never be sent away from home for treatment ; others do best in the cool and bracing climates of our own island ; some require in association with bath treatment the cooler temperatures of northern latitudes or sub-Alpine stations ; and for only a certain number is the summer climate of warm valleys appropriate. The question of altitude should be particularly considered in its influence on the action of baths. Among the thermal baths of Europe there is a wide available range, from 100 to 5000 ft. It may be noted here that for the treatment of circulatory disorders Buxton, Harrogate, and Llandrindod all have a saitable medium elevation, and that Strathpeffer, although nearer to sea-level, has the compensating advantage of a more northern latitude. Hot or thermal baths are best borne in cool places. Indeed, in the case of delicate persons they can only be taken with safety in a cool climate. Otherwise, the enervating effect of heat, added to that of the baths, may bring on a serious condition of what may be called " thermal debility," which is sometimes prolonged for many months, and may even be fatal. Thermal debility, which is the effect of an excessive or too prolonged thermal influence, is a too common and undesirable result of a course of baths. Among the many examples that have come to my knowledge I have sometimes thought that the fault lay quite as much in a bad choice of climate as with the baths themselves. I need not apologise for this incidental reference to what is in truth the most serious danger of spa treatment. We know that heat is one of those powerful stimulants that very rapidly become depressant. Its first effect upon the skin is vascular dilatation and increase of sweat, resulting in compensatory loss of heat. This pronounced and obvious action cannot escape notice, but the reaction of heat comes more slowly than that of cold, and sometimes in a gradual and insidious manner, and it may be after the treatment has ceased. The lessened beat production from thermal applications, the lowering of blood pressure, and the elevation of the temperature of the blood from prolonged and repeated hot baths, all diminish nervous and muscular energy, and bring about exhaustion of the spinal and cerebral centres and the heart. It follows that the reaction to heat must in practice be avoided with as much care as the reaction to cold is encouraged and promoted. In many conditions of senile weakness and premature degenerative changes the indication is for a mildly tonic and sedative climate. The only appropriate remedy, whether of bath or climate, must be temperate, soothing, sedative. FACTORS IN HYDROLOGICAL TREATMENT. The medical use of springs and of baths comprehends a bewildering variety both in the potable water and in the methods of its application. Hitherto, this too obvious diversity has rather obscured the truth that all such treatments have certain essential characteristics in common. The action of pure, sweet, and fresh water is the first of these common factors. The quality of freshness is of the first importance in the administration of waters, and springs differ widely in respect to this quality. It is not necessary to accept without reserve the theory of Armand Gautier that the water of certain thermal springs is in a real sense chemically " new," having the heightened activity of nascent matter. But it is common knowledge that the flowing, or in the old parlance the "living, fresh water of the fountain has a different property from that of the same water when still, contained in reservoirs or bottled. Consequently certain waters produce their most powerful effect when employed either for drinking or externally at the source. The second common factor in these methods of treatment is not less important-namely, heat. For warm-blooded animals living in a cooler medium, heat is measured relatively to the temperature of the body. Plus or minUS applications of heat are naturally inseparable from waters, whether internally or externally used. Baths act in the main as vehicles of energy, of which heat is the chief form. Water is in respect to the human body the commonest and most convenient medium of energy, but it is convenient to include in the category of bath treatment other media, such as dry sand and air, by which heat can be abstracted or conveyed. I Again, inasmuch as baths of different kinds embrace the