In the Northern States diphtheria is most prevalent in October, November, and December; scarlet fever is an April disease, but it may occur at any time. It is easier to spread the infection of scarlet fever and measles than that of diphtheria, but it is not so difficult to disinfect after scarlet fever and measles as after diphtheria. The contagion of scarlet fever does not resist the fumes of sulphur or formalin. Disinfect a room after scarlet fever as for diphtheria but be sure to use also either sulphur or formalin because the contagion can float about a room. Eruptive contagious diseases like scarlet fever, smallpox, and measles so affect the skin that during convalescence the cuticle scales off. In severe cases of smallpox and scarlet fever the entire outer skin of the hand may peel off like a glove. The contagion is always found in the scaling skin. As the patient grows stronger the scales become finer, until at last they lie as mere mealy dust in the hollows of the elbows or other parts of the body. Down to the very last these scales are infectious, and they will retain the infection for months, probably for a year or more. The scales float in the air of a sick-room, fall on the clothing of visitors, are carried away by the shoes of those that leave the room. The scaling may continue for three weeks--it commonly does. These three diseases are infectious before the scaling begins, sometimes before the rash is well out. A very light attack of any of these diseases in one child may infect another fatally. Insist upon keeping a scarlet fever or measles patient out of school until all scaling has ceased. Chickenpox is almost a harmless disease, but it is more infectious than even measles. Be cautious with it because {198} nearly every epidemic of smallpox begins through some one mistaking smallpox for chickenpox, although there is little or no similarity between the diseases. A child with tuberculosis of the lungs or a child infected with acute syphilis should not be permitted to go to school under any circumstance. In the chapter on The Priest in Infectious Diseases will be found an account of the necessity of vaccination as a precaution against smallpox. Tinea Favosa, or favus, is a contagious and a very stubborn disease of the skin, caused by the fungus _Achorion Schoenleinii_. It produces yellowish crusts about the hairs of the scalp and other parts of the body, and it destroys the hair. It attacks also the finger-nails and the skin that is without hair. In the later stages of the disease there is a foul odour. It is one of the most difficult of the scalp-diseases to cure; months and sometimes years are required to get rid of it. A child with tinea should be kept away from school; and his desk and what he touches should be washed with the bichloride of mercury solution. Burn his books and papers.