DISEASES OF THE SKIN AND HAIRS. 113 



complicate the subject, and, with this view, I shall consider 

 the maladies as closely as possible in accordance with Mr 

 Erasmus Wilson's classification, differing only where it is 

 necessary, owing to the peculiarities of these affections in the 

 lower animals. One object attained in applying Mr Wil- 

 son's classification to veterinary purposes is to facilitate com- 

 parisons which it is important for veterinary surgeons and 

 others to make until very decided and independent progress is 

 made in the study of cutaneous diseases in the lower animals. 



Perhaps the first impression produced on my readers may 

 be, that I am uselessly complicating the subject by adopting 

 this course ; but I am persuaded, that any one taking a little 

 trouble to study the matter will find that a good classifica- 

 tion enables us to obtain a clear view of a subject that is 

 usually considered very difficult and puzzling. 



Mr Wilson divides the diseases of the skin into those 

 affecting the general structure, and those affecting the special 

 structure of the skin. 



Under the first head I exclude the diseases which are 

 described as arising in man from the syphilitic poison, and 

 confine my remarks to 



1. Diseases arising from general causes. 



2. Diseases arising from special external causes. 



3. Diseases arising from special internal causes. 



4. Diseases arising from animal poisons, and which con- 

 stitute the eruptive fevers. 



It is, moreover, needless for veterinary purposes, at all 

 events, with our present knowledge of skin diseases in the 

 lower animals, to consider the diseases of the special struc- 

 ture of the skin in eight groups. We can simplify this 

 arrangement by considering 



1. Diseases involving the elementary tissues of the skin or 

 its superficies. 



VOL. ii. 3 B 



