Such are the leading symptoms of fever; their varying intensity may serve as a basis for classification, and they are all of much importance in treatment; but, while no one by itself is diagnostic, we observe that there is some derangement of each of those which are classed as general symptoms. Some are more important than others, but a perfectly normal state of any one must put us on our guard in pronouncing an opinion of the existence of fever.
Corresponding to the variations in symptoms there are differ ences in the intensity of the affection, from its slight and transient form, febricula, to its worst and most deadly shape, malignant typhus. But, while no two conditions can be more widely sepa rated, it is to be remembered that there are numerous intermediate links in regard to severity and danger, which are so closely allied together, and pass by such fine transitions into each other when a large number of cases is examined, that no absolute line of de. marcation can be drawn between them. • There are certain modes of division, which, so far as they con cern diagnosis, must here shortly be referred to. Thus, there are epidemic, endemic, and ephemeral fevers. This classification cannot be regarded as of much practical value, as we know not that it corresponds to any real difference in the ultimate nature of the disease. We know not whether an endemic fever may ever become epidemic, nor by what circumstances such a change of character can be produced. The only importance of these dis tinctions is derived from the observation that each class presents for the time being certain peculiarities, and the general features of individual examples have a degree of resemblance to each other. It is indeed surprising how great a similarity all cases of fever have to each other for a given time and in a given place, and how much they differ from cases occurring at another time, or in another locality.
1. Epidemic fevers, spreading probably by means of some poison suspended in the atmosphere, are generally believed to possess the property of commu nication by infection ; with their specific characters the student should make himself acquainted by observation, as soon as possible, whensoever an epidemic begins to prevail.' The epidemic typhus and relapsing fevers offer good ex amples of this class.
2. Endemic, or endemial fevers, not so clearly infectious, but arising appa rently from some local influence, are generally found also to present, in each locality, distinctive characters, which must soon be familiar to a practitioner in any given place.
3. Ephemeral fevers, breaking out quite unexpectedly, in consequence most probably of a sudden atmospheric change, and disappearing with the same rapidity, differ from the other two chiefly in their being comparatively less severe, and commonly marked by one prominent symptom. A very good example may be seen in the outbreaks of influenza. To this fever we have assigned a separate place in our classification, solely because its symptoms are so peculiar, and its occurrence so frequent.
Another mode of division is that obtained from the presence and absence of cutaneous eruption, and its special characters. If it be true that the same cause cannot engender a fever with, and one without spots, and if it be further true that the same cause cannot generate fevers with spots of dissimilar kinds, it is plain that the correct discrimination of fever spots would lead also to the true diagnosis of species of fevers. But this is not yet proved. And, at all events, the absence of spots altogether neither warrants the conclusion that the disease is not fever, nor that it belongs to a particular class of which this circumstance may be considered characteristic. Further, if it be true that these different species of fevers are prone to affect special organs more than others, and each species a different organ, it would be a most valuable indi cation in treatment; but as this is yet sub judice, we must receive the probability with great caution, and only the more closely investigate the symptoms appertaining to each, forming our judg ment of the character of the fever from their co-existence, rather than assuming their presence from the type of fever.
In a treatise on diagnosis it is obviously impossible to discuss disputed points in semeiology, and all that can be done in this place is to point out the different characters the spots are liable to present. In hospital practice, the patient often exhibits, especially about the neck and upper part of the chest, a number of minute puncta of a blood-stained appearance, perfectly unaffected by pressure with the finger, and having more or less of a triangular shape; when once observed, they can be easily recognized and distinguished. They are merely flea-bites, but they have this value in diagnosis, which is often overlooked, that the accompanying ecchymosis indicates depressed vitality. The true fever spots present three varieties, each of which may be mingled with petechise.