HYPER^MIA AND ANAEMIA OF THE SKIN. 



451 



of the surface, caused by a blow, might be called erythema traumati- 

 cum. Such a variety of names for hyperaemia of the skin is quite use- 

 less, and, as some of the inflammatory cutaneous affections, when ac- 

 companied by redness, are also called erythema, it only creates mis- 

 understanding and confusion. Partial hypersemia of the skin, more- 

 over, is the first symptom of most of the acute and chronic exanthe- 

 mata, in whose subsequent course exudation is thrown out either 

 within the skin or upon its surface. Finally, partial cutaneous hyper- 

 semia is very often observed in certain febrile diseases, without our 

 being able to account for its occurrence. In such cases the hyper- 

 aemia usually is limited to a very small circumscribed area, forming 

 rounded or irregular red spots, varying in size from that of a lentil to 

 that of a farthing, and is thus called roseola. This name, however, is 

 not applied exclusively to the red spots of simple hyperaemia (macula), 

 but also to the small red nodules arising from an infiltration of the 

 skin combined with hyperaemia (papula). Typhoid fever, the typhoid 

 stage of cholera, and other infectious disorders, are accompanied by 

 roseola, but it also is by no means rare in the febrile, gastric, and intes- 

 tinal catarrhs of children, as well as in inflammatory diseases of the 

 brain and lungs. When we can discover a cause for the fever, we call 

 the roseola a symptomatic roseola / when no cause for the fever can 

 be found, the eruption is said to be idiopathic. To the latter class 

 belong the so-called roseola sestiva, ros. autumnalis, ros. infantilis, 

 and some of the affections entitled measles ("Rfltheln"). r 



The only symptoms of erythema are reddening of the skin and an 

 augmented sense of heat. The hyperaemic surface becomes blanched 

 if the blood be expelled from the skin by pressure, while the redness 

 arising from haemorrhage into the cutis is not effaced by pressure. 

 When the reddened spot is likewise much swollen and painful ; when 

 the pressure leaves a white spot instead of a yellow one behind ; when, 

 after the redness subsides, the epidermis scales off, the disease is not 

 simple hyperaemia, but inflammation with infiltration. 



Anaemia of the skin is an important symptom of poverty of the 

 blood. It also arises from exposure of the skin to a very low temper 

 ature, both owing to the physical action of cold and to the contraction 

 of the cutaneous muscles to which cold gives rise. Both of these ef- 

 fects render the skin denser and more resisting, and thereby impede 

 the influx of blood into the capillaries. This effect is increased by the 

 contraction of the smaller arteries which takes place at the same time. 

 Finally, a partial anaemia or ischcemia of the skin may arise independ- 

 ently of the influence of cold, from spasmodic (?) contraction of the 

 cutaneous muscles and muscles of the arterial walls. This phenome- 

 non is most frequently observed during the rigor which ushers in a 



