that the effect of education had been, even in the midst of a rapidly-increasing population, to diminish the absolute number of children admitted to asylums. So, of the group described as teachers, schoolmasters, schoolmistresses, governesses, professors, and lecturers, the proportion admitted to asylums was less than that of any other profession. This statement should dispose of much of what is said about the ordinary routine of school occupation leading to mental disease. While pupils who are stimulated or pressed, by cramming, to over-exertion may suffer injury, a lively exercise of the mental faculties on some varieties of subjects, which is the most that the majority of school-children attain, is more likely to be promotive of vigor. The fact that insanity prevails most among agricultural laborers in the rural counties, where the standard of education is lowest, and mental vacancy is least interrupted, tends to show that absolute blankness of mind, like the non-use of a physical faculty, promotes disease. So with teachers: while the demands on their brains are constant and call for vigorous exercise, they are, as a rule, seldom of a kind to involve overwhelming pressure, or so irregular as to admit of intervals when the mind is wholly unemployed and liable to morbid reaction.
Poisons developed in the Body.—On this subject Dr. Benjamin W. Richardson says: "In my reports to the British Association for the Advancement of Science, I have pointed out that the substance amylene, an organic product which can be easily constructed in vital chemical changes, produces phenomena identical with those of somnambulism and with some of the phenomena of hysteria. I have pointed out, in the same reports, that another organic product, called mercaptan (sulphur-alcohol), causes, when inhaled, symptoms of profoundest melancholy, and that, in the process of being eliminated by the breath, it gives to the breath an odor which is identical with the odor evolved in the breaths of many patients who are suffering from the disease called melancholia. From these observations I have ventured to suggest that various forms of mental affection and of nervous affection depend for their development on the presence in the body of organic chemical compounds, formed and distilled through an unnatural chemical process carried on in the body itself. I have endeavored to develop this subject somewhat further by my researches on the action of lactic acid on animal bodies. I have shown by experiment that this acid, diffused through the body by the blood, acts as a direct irritant upon the lining membrane of the heart, the endocardium, and all the fibro-serous membranes of the body, so that a synthesis of heart-disease and rheumatism can be established by its means. Lactic acid is the most copious product thrown out in the disease called rheumatic fever, and, as many of the phenomena resulting from that disease take the same form and character as those producible by lactic acid, I infer from the best evidence attainable that this acid, the product of a fermentative change going on in the body during acute rheumatism, is the cause of the secondary structural affections which so frequently follow acute rheumatism. It has been for some time past observed by several able physicians that persons who are suffering from the affection known as diabetes give off a peculiar odor from their breath—an odor which to some is like that of vinegar, to others of sour beer, to others of a mixture of ether and chloroform, to others of acetic ether. I should compare it myself to the odor of grains as it is detected in a brewery. When this odor is observed in the breath of diabetic patients, it frequently happens that they become sleepy, cold, and unconscious, with the results of coma and death. At one time it was supposed that these phenomena were uræmic, and were due to the presence of urea in the blood; but the absence of convulsion and of some other symptoms destroys this hypothesis, or at all events shakes it. It is now believed that the symptoms owe their origin to the decomposition of the diabetic sugar which is in the body, and to the production from that decomposition of a volatile ethereal fluid called acetone a fluid which has been discovered in the blood and secretions of these affected persons, who are said therefore to be suffering from the disease 'acetonæmia.' From the action of acetone upon animal bodies