SMALL-POX IN THE VACCINATED.--When small-pox occurs to those that have been formerly vaccinated, the disease, in almost every instance, is much altered or modified in its character. Indeed in children, in whom of course vaccination has been but comparatively lately performed, small-pox when it occurs will, in the majority of cases, be so mild that the real nature of the disease will be with difficulty determined: so mild, that again and again has a parent been heard to exclaim, "Surely these few scattered pimples cannot be the small-pox!" If, however, as the pimples progress, they are narrowly watched, and are seen to become depressed in their centre; if there has been the precursory rigor, etc.; and if the source of the disorder can be traced to some case of undoubted small-pox, the child in fact having been exposed to contagion, no doubt ought to exist in reference to the nature of such a case, however slight may be the character of the disease. The usual progress, however, of small-pox modified by vaccination is as follows. The first stage is the same usually as in the natural form of the disease. As soon, however, as the eruption appears, the modifying power of the vaccination becomes apparent. The eruption will be found to be generally both less in quantity and more limited in its extent; or if even it should come out profusely, and cover a large extent of the surface of the body, still the controuling power of the vaccination will immediately show itself after its appearance,--first, in the complete subsidence of all the febrile symptoms which will now take place; and, secondly, in reference to the eruption, part of which will die away at once, and the remainder will by the fifth day be filled with the opaque yellowish fluid, then dry up, becoming hard and horny, and falling off will leave a mottled red appearance of the skin, and now and then slight pitting. Such is the usual progress of the disease: subsequent to vaccination, it is a mild and tractable disorder. It is right, however, to mention that small-pox has occurred even to the vaccinated in almost as severe a form as the confluent natural small-pox, and running its regular course unaltered or unmodified. Such instances, however, are extremely rare, and form the exceptions to the general rule; for "no reasonable doubt can be entertained, from the abundance of facts now before the world, that such modification is the law of the animal economy, and that the regular or natural progress is the exception."