understand epileptic attacks and cannot be expected to distinguish them from hysterical convulsions and other diseases. It does not necessarily follow that cases of epilepsy should be withdrawn from the school, but medical advice should always be had. NEURASTHENIA.-Neurasthenia or nerve fatigue may be shown by irritability or sleeplessness and other indications threatening a nervous breakdown. This may be due to irregular habits, want of proper sleep, lack of suitable food, poor hygienic conditions, or simply from the child being pushed in school beyond his physical or mental capacity. Excessive fear or morbid ideas, bashfulness, undue sensitiveness, causeless fits of crying, morbid introspection, and self-consciousness may also be symptoms of a neurasthenic condition, and call for investigation and for the teacher's sympathy and winning of the child's confidence to prevent developments of a more serious nature. The teacher should know that forgetfulness, loss of interest in work and play, desire for solitude, untidiness in dress or person, and like changes of character are sometimes incidental to the period of puberty. DEFECTIVES.-Mentally defective children in the public schools exhibit certain common characteristics which soon become evident. The typical incorrigible child of the primary grades often is a mentally defective child of the excitable type. They are destructive, cruel to smaller children, and often precocious sexually. Certain cases show marked moral deficiency. Mentally defective children must be distinguished from those who are only temporarily backward as a result of some removable cause such as defective vision, impaired hearing, adenoid growths, or as the result of unhappy home conditions, irregular habits, want of proper sleep, lack of suitable food, bad hygienic conditions, etc. Teachers should refer to the medical inspectors for examination children who, without obvious cause, such as absence or ill health, show themselves unable to keep up in their school work, who are unable to fix their attention, or are incorrigible. A careful lookout should be kept for children showing sexual perversion, for one sexual pervert may demoralize a whole school. Vaccination.-Vaccination should be required of all children before they are permitted to attend school. The evidence of a successful vaccination usually accepted is a physician's certificate or a characteristic scar. For the indices of a successful take see page 11. children should be vaccinated before entering school and again before entering high school. School REFERENCES The following references have been used in the preparation of this chapter, especially the books of Shaw and Hogarth. Shaw, Edward R.: "School Hygiene." The Macmillan Co., N. Y., 1902. Hogarth, A. H.: "Medical Inspection of Schools." Oxford Medical Publications, London, 1909. Gulick, L. H., and Ayres, L. P.: "Medical Inspection of Schools." New York Charities Publication Committee, MCMVIII. Stevens, E. M.: "Medical Supervision in Schools." Baillière, Tindall, and Cox, London, 1910. Baginscky, Adolf: "Handbuch der Schulhygiene." Bd. I, 1898; Bd. II, 1900. Ferdinand Enke, Stuttgart. Transactions of the International Congress on School Hygiene. Bowditch, H. P.: "The Growth of Children Studied by Galton's Method of Percentile Grades." Twenty-second Annual Report of the State Board of Health of Mass., 1890, pp. 479-522. Weyl, Theodor: "Handbuch der Hygiene." Vol. VII, Erste Abt, Schulhygiene, Jena, 1895. SECTION XII DISINFECTION CHAPTER I GENERAL CONSIDERATIONS Definitions. Disinfection means the destruction of the agents causing infection. An object is said to be infected when contaminated with pathogenic microorganisms. It is disinfected by destroying these organisms, whether they are in the substance or on the surface of that object. Disinfection, then, deals only with destroying the vitality of those minute forms of life which cause disease. It does not mean the destruction of all the lower forms of animal and vegetable life that may be in or upon an object-this is sterilization. STERILIZATION.—All processes which sterilize necessarily disinfect, but all disinfecting processes by no means sterilize. The distinction between disinfection and sterilization arises principally from the fact that spores have a much greater resistance to all influences which de stroy the vegetative cells. Fortunately, none of the pestilential diseases of man which occur in widespread epidemics, so far as known, are caused by microorganisms with resistant spores; therefore the usual processes of disinfection may be thoroughly efficient, yet leave many harmless and hardy forms of microscopic life alive. In other words, sterilization is rarely necessary in public health work, except in the case of anthrax, tetanus and other spore-bearing infections. ANTISEPTICS.-Antiseptic substances prevent decomposition and decay. Such substances retard or prevent the growth and activity of microorganisms, but do not necessarily destroy them; that is, antiseptics delay or prevent fermentation and putrefaction without destroying the microorganisms which cause these processes. There is a great difference between the antiseptic and the disinfecting power of most substances. For instance, a solution of formalin will restrain the development of most bacteria in the proportion of 1 to 50,000, but it requires a 3 to 5 per cent. solution of this liquid to kill the bacteria in a reasonably short time. As weak a solution of bichlorid of mercury as 1 to 300,000 will sometimes prevent the germination of anthrax spores, whereas it requires a 1 to 1,000 solution to destroy them. Saturated solutions of salt or sugar will preserve meat, vegetables, and other organic substances; that is, they are antiseptic in their action but not germicidal, as they have small powers of destroying microorganisms. ASEPSIS. Asepsis means freedom from or absence of living microorganisms and is practically equivalent to sterilization. GERMICIDE. A germicide is a substance or agent which destroys germs. Germicides and disinfectants are interchangeable terms, as both are used to indicate the destruction of microorganisms. Most germicides used in public health work are potent enough to sterilize objects with which they come in contact. DEODORANT.-A deodorant is a substance which has the power to destroy or to neutralize the unpleasant odors arising from organic matter undergoing fermentation or putrefaction. Such substances must be distinguished carefully from disinfectants. Deodorants destroy smells; disinfectants destroy germs. Many of the disinfecting agents are also deodorants, but all deodorizing substances are by no means disinfectants. For example, charcoal will absorb the malodorous gases arising from putrefying and fermenting materials, but it is inert so far as its power to destroy the cause of these processes is concerned. Formalin, on the other hand, is a true deodorant and disinfectant, as it combines with the organic matter to form new compounds which are both odorless and sterile. Bichlorid of mercury, while a very potent germicide, has practically no immediate effect upon odors. The volatile oils and other substances having a pungent odor are not deodorants; they simply cover up one smell with another. Nature's Disinfecting Agencies.-In nature many forces are constantly at work to destroy infection and thereby limit the spread of the communicable diseases. It is the duty of the sanitarian to encourage the use of these natural disinfecting agencies; they are dilution, sunlight, dryness, and symbiosis. Sunlight is a great destroyer of germ life. Few microbes, especially the pathogenic ones, can live in the direct bright sunlight many hours. Dryness is another natural condition that is destructive to many of the minute forms of life with which we have to contend. The combination of dryness and sunlight is quite as good, if not better, than the ordinary fumigating processes which are commonly used in practical disinfection against surface contamination. Dryness, sunlight, and cleanliness are the keynotes of sanitation in the modern acceptation of the term. We now know that most of the pathogenic microorganisms do not grow and multiply in our environment. For the most part they die when wafted into the air or carried into water or deposited in the soil. It is only occasionally that they find conditions favorable for development in foods such as milk and meat, and exceptionally in water. Further, it is to be noted that ordinarily it requires a certain number of microorganisms to produce infection. It is quite conceivable that a single typhoid bacillus or a single tetanus spore may "kindle a conflagration." Experimental evidence with the infections upon laboratory animals teaches the lesson that ordinarily an animal is capable of taking care of minute and dilute amounts of infection. Dilution, attenuation, and the conditions of our environment, unfavorable to most germs. harmful to man, therefore protect us in no small measure against the communicable diseases. Cleanliness.-Cleanliness is a very important adjunct to the work of disinfection. In fact, cleanliness lies at the base of all our sanitary measures. The mere act of cleaning removes some of the adherent microbes from the surface and the ordinary scrubbing and washing result in the final destruction of many more. Dry dusting and sweeping serve only to stir up dust and infection, which settle down again upon the same or other surfaces. Cleanliness serves another important purpose, so far as infection is concerned; it removes the organic matter on which and in which bacteria may find favorable conditions for prolonging life and virulence. The modern conception of cleanliness has expanded with the growth of the sanitary sciences. We now aim at biological cleanliness as well as esthetic cleanliness. This includes not only the removal of organic matter, but the destruction of insects and vermin, and their feeding and breeding places. So far as personal cleanliness is concerned, the two important acts to prevent infection are: (1) Washing the hands before eating and (2) keeping the fingers away from the mouth and nose. In the wholesale disinfection which must be practiced to check widespread epidemic diseases due to bacterial infection we are largely limited to the use of the agents which nature has constantly at work to destroy such infection. Against a single case of communicable disease or against a limited infected area we may employ aggressive measures such as steam and strong chemicals; but when a disease, due to bacterial infection, has spread over an extensive district these methods must be supplemented by all the resources of nature. The people must be educated so as individually to employ intelligent measures to avoid the infection. Cleanliness must be more scrupulously practiced than ever, sunlight and dryness must be given their fullest opportunity to operate even at the expense of a few faded carpets or colors. Symbiosis. Many pathogenic microorganisms are destroyed in the process of putrefaction and fermentation. They die in the fierce struggle for existence going on in these processes of decomposition. For the most part the hardier saprophytic forms of life overpower and kill the disease-producing microorganisms having comparatively feeble powers |