ERYTHEMA. 339 



inflammation so as to make them agree with those employed 

 in cutaneous pathology, and leave it to our readers to simplify 

 matters farther by means of such abstractions as have just 

 been hinted at. 



§ 288. — 1. The erythematous e.vanthem. Simple erythema, 

 even when it amounts to a positive turgescencc of the cutaneous 

 capillaries, would hardly be supposed likely to afford materials 

 for histoloo^ical investi^iation, were it not for the recent obser- 

 vations of R. Volkmann and Steudener (Centralblatt, 1868, 36) 

 on erysipelas ; these observers prove that in the course of 

 this essentially erythematous inflammation of the skin there 

 occurs a very extensive migration of leucocytes into the cutis 

 and subcutaneous areolar tissue ; true, these leucocytes disap- 

 pear in two or three days by disintegration and absorption ; 

 still, they serve to show how easily a simple erythema may 

 pass into those higher grades of inflammation, which it 

 invariably precedes. Moreover, even a transient erythema 

 usually leaves some vestiges of its presence behind it. It is 

 usually followed by a desquamation of the outermost layer 

 of the epidermis, whether branny (desquamatio furfuracea) or 

 follaceous (desquamatio memhixmacea). This phenomenon can 

 only be explained by the close connexion which subsists between 

 the nutrition of the epidermis and the changes occurring in the 

 papillary body. Every hyperaemla involves a disturbance, an 

 interruption in the nutrition of the epidermis. The details of 

 this are not known. So much seems certain, that this disturb- 

 ance causes a separation of the epidermis into an outer, less 

 nourished, and an inner, better nourished layer. This separa- 

 tion manifests itself as a real though imperfect cleavage, or 

 rather loosening of the substance of the cuticle between its 

 horny and its mucous strata, without the intervention of exuda- 

 tion. When in the course of growth the oldest portions of 

 epidermis come to be shed, a simultaneous detachment of the 

 deeper and younger layers of the horny stratum bears witness 

 to their premature death and consequent separation from their 

 native soil. 



We distinguish between diffuse and circumscribed erythe- 

 mata. It often happens that an erythema which is at first 

 diffused, becomes concentrated in course of time at one or more 



