It is highly contagious, and for this reason perhaps it is usually met with in infancy and early childhood. Sometimes, though by no means constantly, the eruption is preceded for twenty-four or thirty-six hours by slight feverishness; but oftener the appearance of the rash is the first indication of anything being the matter. It shows itself in the form of small pimples, which in a few hours change into small circular pocks containing a little slightly turbid fluid. They appear on the forehead, face, and body, but very rarely on the limbs; they enlarge for some two or at most three days, then shrivel and dry up; and at the end of a week the crusts or scabs fall off, scarcely ever causing any permanent pitting of the skin. They are usually not above twenty or thirty in number, though every now and then they are much more numerous without any obvious reason. Their distinction from the small-pox eruption consists not only in the smaller size of the pocks, and in the entirely different course which they run, but also in the fact that two or three successive crops of the eruption appear in the course of five or six days, so that new ones, those at maturity, and those on which the crusts have already formed, or from which they have already fallen, may be seen on the child at the same time. This is sufficient of itself to establish the difference between the two diseases, and also to distinguish between chicken-pox and the milder variety of small-pox which is sometimes observed in children who have been already vaccinated. =Measles= is a disease with which almost everyone is familiar, and one which with proper care is not generally attended with danger. Its great risks are twofold; first, that of its being complicated with bronchitis, or inflammation of the lungs during its progress, and next of its being followed by an imperfect recovery, and by the awakening into activity any tendency to scrofulous or consumptive disease. On these two accounts the disease is not to be made light of, and special watchfulness is to be exercised during the whole time of convalescence. It is also unwise when one child in a family is attacked by measles to expose the others, as is often done, to its contagion, in order, as people say, 'to get it over;' for its mildness in one case furnishes no guarantee of its mildness in another, and the danger of the disease is almost in exact proportion to the tender age of those who are attacked by it.