The period of incubation, as it is called, has no dis' tinct charac ters. During the incursion of the fever, before any cutaneous eruption has appeared, there are certain indications which, more or less definitely, point to what is about to occur-1. In measles, it is attended with coryza. 2. In scarlatina, there is sore throat, and the appearance of the tongue is peculiar. 8. In varioloid eruptions, pain in the back is present. 4. Erysipelas is not marked by any special prodromata ; there is a general sense of malaise, sometimes sore throat, and, not unfrequently, a dull, aching pain, or pricking sensation, in the part that is to be at tacked.
1. Coryza belongs also both to common catarrh and to influenza. In the former there is much less fever ; in the latter, if the fever be equal, there is much more depression. The affection of the mucous membrane in measles is marked by injection of the conjunctivas ; in catarrh and influenza it is more confined to the throat and bronchi. I have felt for a moment perplexed by the effects of a fit of crying in a young person with slight febrile disturbance, and the hint may be useful to others.
2. The sore throat of scarlatina is characterized by profuse redness of the fauces, without tumefaction to any extent in the first instance. That which sometimes accompanies simple fever presents less diffuse redness ; in quinsy it is always associated with much swelling. In all of these the distinctions derived from febrile symptoms are to be viewed in connection with the local state ; when the characters of scarlet fever most nearly approach to typhus the redness is most marked, and it has a livid hue ; in quinsy, when the swelling is so slight as to cause any doubt, the febrile state is scarcely appre ciable. The sodden tongue of quinsy has always but little analogy to that of fever.
In a well-marked case of scarlatina, there are generally to be seen on the tongue a number of round elevated papilla, which, in the early stage, protrude through a white fur, giving it a dotted appearance, and at a later period stand out from the smooth red surface, producing what is generally spoken of as the " strawberry" tongue. This appearance cannot serve for the diagnosis of 'doubtful cases, except, perhaps, in a retrospective view.
3. The pain of the back in variolous attacks is sometimes most remarkable. It is more intense than any similar condition observed in ordinary fever, in • which pains in the limbs generally are sure to accompany any local pain in the back, and depression is observed rather than excitement; the fever ex isting prior to the eruption of smallpox, when pain in the back is felt, is usu ally of an active form. A distinction between this local pain and that of lumbago, in the general acceptation of the term, may be drawn from its posi tion : the latter affects the muscles at the side of the spine, and is, conse trendy, much aggravated by movement ; the former is more central in situa tion and is less affected by change of posture. The subject of nephritis will
occupy us at a later period. Other causes of pain in the back are not attended with symptoms of fever.
Eruptive fevers vary very greatly in intensity prior to the appearance of the cutaneous affection ; and it fortunately happens that, when the fever is most severe, the local indications just mentioned are most striking. In slight cases, where the prac titioner is most likely to be thrown off his he is seldom called till the appearance of the eruption no room for hesitation as to the cause of the attack.
The eruptions present certain distinct forms, which, in their full development, become the basis of distinction between these diseases, as they also separate them widely from other forms of fever. Their characters are, however, occasionally so obscure, that, notwithstanding all the aid derived from antecedent and consequent symptoms, cases do occur which are not free from ambiguity. The principal features are the following :— 1. eruption consists of a mottled redness, which appears in the form of numerous rose-colored spots, papular, very slightly elevated, and grouped in crescentic patches; the eleva tion scarcely perceptible to the touch, and without any sensation of hardness. It is first observed about the back and loins, and subsequently spreads until it covers the whole body, in most =dicis.
2. Scarlatina.—Here we find a diffused redness, of more or less brilliancy, especially affecting the front of the neck, spreading down on the chest, and also appearing at the bend of the elbow and on the legs, where, sometimes, it is more extended and gene ral than on the upper part of the body. It commonly begins with the neck, and assumes the form of minute points of redness, which are in no way elevated, and rapidly coalesce. There is no feeling of hardness or appearance of boundary line, though the 3. Varioloid Eruptions generally first appear on the face, pre ceded by patches of redness, which have a hard, gritty feeling to the finger ; upon these patches minute vesicles, more or less numerous, form ; some, or all of them, acquire gradually a larger size, become filled with lymph, which passes quickly into pus, and are marked by a distinct depression in the centre. In modi fied smallpox, after vaccination, the eruption may be very scanty indeed—may, perhaps, only show itself on the chest—and few or ' none of the vesicles ever enlarge to the appearance of variolous pustules.