388 DISEASES OF THE SKIN. 



to resist the accumulated exudation for some time, the contents of 

 the vesicles gradually benome milky and pus-like, on account 

 of the entrance of colorless blood-cells into the tissues (eczema 

 pustulosum). 



In other cases the vesicles burst or are scratched open; the skin 

 is dark red in large blotches, and is marked by fine furrows 

 which correspond with the location of the ruptured vesicles; the 

 eczematous exudation oozes freely out of the upper surface (eczema 

 rubrum). It is a common occurrence to see the detachment of 

 small portions of tissue which are located between the numerous 

 furrows in the epidermis. Thus the whole surface of the eczema 

 is stripped of its horny layer and may become filled with pus. 

 The oozing liquid dries rapidly and becomes a scab or crust (eczema 

 impetiginosum), which is pushed away gradually by the consecu- 

 tive exudation, and finally becomes hard, dry, and firm. Inflam- 

 mation and swelling become gradually lessened under the crust, 

 and we have the formation of a firm epidermic cover, from which 

 the crusts gradually become detached. The diseased membrane, 

 which is now exposed, is not swollen to any great extent, but very 

 red (sometimes marked with dark, livid pigmentations), and covered 

 with numerous loose scabs, which constantly fall off and are re- 

 newed from time to time (eczema squamosum). 



Etiology. The etiology of eczema is of great importance for 

 establishing the correct prognosis, as no cure can be obtained until 

 after the cause of the trouble is removed. The first thing we must 

 do is to lessen the mechanical irritations, such as appear under the 

 collar and on the testicles. But the lesions which the patient 

 infiicts upon himself are of very much more importance, for we 

 see it in all forms of itching eruptions of the skin, in erythema, 

 in cases of parasites of the cutaneous membrane — flies, lice, acari — 

 in great accumulations of dirt, scabs, and falling out of the hair. 

 We also have the appearance of eczema which extends very fast, 

 and in some cases may go all over the body. 



As regards the second group of agents which cause eczema, they 

 are chemical irritants, especially those which have an influence 

 upon the tissues, such as acids, alkalies, mixtures of mercury, also 

 tar and carbolic salves, combinations of ether and oil of turpen- 

 tine, of mustard, and also tar-soap. 



The third group is formed by a number of thermic irritations. 



