Redness does not suffice for the existence of inflammation, for it may be found in the absence of other evidence of the latter. The diffused redness, often extensive, of birth-marks, that from venous obstruction or temporary congestions, from vaso-motor disturbances--the section of the sympathetic furnishing a well-known instance--are examples of non-inflammatory redness. Inflammation may even be present without redness, as may be constantly observed in the occurrence of parenchymatous inflammation and of the chronic interstitial varieties. The heat of inflammation is one of the most important clinical features, yet not indispensable, as appears from its absence in chronic interstitial forms of inflammation. In the acute varieties of inflammation an elevated temperature is constant, and its observation and record furnish a most valuable means of determining the beginning and progress of an inflammation, which, for a time, may furnish but little additional evidence. The heat of inflammation is the prominent characteristic of inflammatory fever, and it is the study of this variety of fever of late years which has resulted in an intelligible and relatively satisfactory theory concerning fevers in general. Information of much value is to be found in the recent work of Wood,[3] which contains abundant historical information, as well as extensive original observations and conclusions. [Footnote 3: _Fever: A Study in Morbid and Normal Physiology_, H. C. Wood, A.M., M.D., Philadelphia, 1880. (Reprint from the _Smithsonian Contributions to Knowledge_, No. 357.)] Inflammatory fevers are distinguished from idiopathic forms. The latter variety includes the occurrence of fever as an attribute of the disease concerned, the more characteristic symptoms of which follow the febrile outbreak. Local inflammatory processes may take place during the progress of the disease with its fever, but such processes are co-effects of the cause of the latter, rather than its cause. Most of those diseases in which fever occurs as one of the joint effects of the cause of the disease, are included among the infective or zymotic classes. The inflammatory fevers are those attending an acute inflammatory process, and are secondary to, and occasioned by, the latter. The type of this variety is seen in the fever occurring during the progress of a wound, whether its course is toward healing or extension. Such {38} traumatic fevers are characterized as septic or aseptic; the former including the conditions of septicæmia and pyæmia. The aseptic traumatic fevers, as described by Volkmann,[4] are those which pursue their course with an elevated temperature, but without most of the other febrile phenomena. [Footnote 4: _Beiträge zur Chirurgie_, Leipzig, 1875, p. 24; _Sammlung Klinischer Vorträge_, No. 121, Genzmer und Volkmann.]