TEGUMENTAL SYSTEM. 409 



bid excrescences, since they are unexceptionably present in horses, 

 as well as in asses and mules. 



Rete Mucusum. 



The rete vel corpus mucosum consists of a fine, delicate, lami- 

 nated tissue, interposed between the cuticle and cutis, and serv- 

 ing as their connecting medium ; so that the two parts I have 

 been describing are, in fact, nowhere in contact with each other. 

 It is to this substance that the skin owes its colour ; in proof of 

 which, as was observed but now, if either the cutis or cuticle of 

 a black horse be examined in its detached state, it will be found 

 to be, in itself, colourless. Again, the cutis vera of the Negro is 

 as white as that of the European; the only difference in their 

 skins consisting in the colour of the rete mucosum, which in the 

 latter is black. 



Composition, — This part is with difficulty demonstrable in a 

 separate state from the others. We may detach it by putrefac- 

 tion from the cuticle, but we succeed only with great pains in 

 stripping it from the cutis, and this is best attempted by macera- 

 tion in hot water : the skin of a black horse, and a part bare of 

 hair, should be selected for the purpose. It is (as its name im- 

 plies) a viscous mucilaginous matter, clothing the delicate vessels 

 and nerves of the cutis in their way to the surface, and appearing 

 to afford them some protection from outward impressions, and to 

 assist in preserving their integrity of structure. It has been com- 

 pared to the pigment of the eye ; and, as far as their general ap- 

 pearance is the ground of analogy, certainly not without reason. 



Colour. — In most animals there appears to be a general rela- 

 tion in colour between the skin, the hair, and the eyes. In 

 black horses we invariably find the skin black, and the eyes dark- 

 coloured ; on the contrary, in the milk-white and cream-coloured 

 breeds, the skin is white or colourless, and the eyes red or ferret- 

 ty. In brown, bay, and chestnut horses, the rete mucosum par- 

 ticipates of the colour of the coat ; in pieballs, skewballs, &c. it 

 varies its hue in places with the change in colour of the hair. 

 The Negro has black hair and black eyes ; the Mulatto, black 

 hair and dark eyes ; the Albino (in whom by som.e this substance 

 is thought to be wanting) light hair and red eyes. 



Regeneration. — This part, when destroyed, as it occasionally is 

 by abrasion or ulceration, appears to be with difficulty regener- 

 ated : some say that it never is. We know that after broken 

 knees, white hairs are frequently seen upon new skin ; but, in 

 the course of time (unless the part go bare), it generally becomes 

 covered by hair of an uniform colour with the coat : this inclines 

 me to think that the rete mucosum is reproduced. Again, new 

 3 G 



