DISEASES OF THE SKIN. 



By JAMES LAW, F. R. C. S. V. S., 

 Professor of Veterinary Science, eic , Cornell University. 



As we find thein described in systematic works, the diseases of the 

 skin are very numerous and complex, which may be largely accounted 

 for by the fact that tlje cutaneous covering is exposed to view at all 

 points, so that shades of difference in inflammatory and other diseased 

 processes are easily seen and distinguished from each other. In the 

 horse the hairy covering serves to some extent to mask the symptoms, 

 and hence the nonprofessional man is tempted to apply the term 

 " mange " to all alike, and it is only a step further to apply the same 

 treatment to all these widely different disorders. Yet even in the hairy 

 quadruped the distinction can be made in a way which can not be done 

 in disorders of that counterpart and prolorgation of the skin — the 

 mucous membrane, which lines the air passages, the digestive organs, 

 the urinary, and generative apparatus. Diseased processes, therefore, 

 which in these organs it might be difficult or impossible to distinguish 

 from each other, can usually be separated and recognized when appear- 

 ing in the skin. 



Nor is this differentiation unimportant. The cutaneous covering pre- 

 sents such an extensive surface for the secretion of cuticular scales, 

 hairs, horn, sebaceous matter, sweat, and other excretory matters, that 

 any extensive disorder in its functions may lead to serious internal 

 disease and death. Again, the intimate nervous sympathy of different 

 points of the skin with particular internal organs renders certain 

 skin disorders causative of internal disease and certain internal dis- 

 eases causative of affections of the skin. The mere painting of the skin 

 with an imi)ermeable coating of glue is speedily fatal ; a cold draught 

 striking on the chest causes inflammation of the lungs or pleura ; a skin 

 eruption speedily follows certain disorders of the stomach, the liver, the 

 kidneys, or even the lungs ; siuiirle burns of the skin cause inflamma- 

 tions of internal organs, and inflammations of such organs cause in their 

 turn eruptions on the skin. The relations — nervous, secretory, and 

 absorptive — between the skin and internal organs are most extensive 

 and varied, and therefore a visible disorder in the skin may point at 



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