MELANOSIS AND OSSIFICATION. 
387 
same situation. These deposits were both divided in separating 
these limbs from the body. 
Having already noticed the state of the vulva and tail, I have 
only to remark that the tumours in these situations were encysted, 
moveable, firmer, more defined, and tuberiform, than any others, 
except the principal one in this subject : they were placed in the 
cellular subcutaneous tissue superficially, having little or no con- 
nexion with the muscles underneath. 
The skin at the extremity of the tail was enormously thickened 
by a deposit of melanotic matter into its interstices, forming a club- 
like termination. 
The Eyes . — In giving the history of this case, I omitted to state 
that this mare was totally blind for some years. My attention was 
now directed to these organs, with the view of ascertaining whether 
this disease had produced their destruction. Such, however, is 
not the case : cataract has destroyed each eye, but the left pre- 
sented an interesting specimen of disease, viz., an ossification of 
a triangular figure, of the cellular substance of the vitreous humor , 
filling the middle and one-third of the posterior chamber, having 
the capsule of the lens firmly attached to its anterior surface, being 
connected also posteriorly firmly to the retina and tunica sclerotica 
by dense bands. 
Remarks. — The disease called melanosis by medical and vete- 
rinary writers, black cancer by Dupuytren, and melanoma by 
Dr. Carswell, may be considered to be a morbid deposit of a black 
or blackish-brown colour, occurring in almost every part of an 
animal’s body. It has been seen in man, and in a variety of the 
smaller animals, but appears to be a much more common disease 
in horses than in man or other animals. It has been found to exist 
in almost every organ and tissue of the horse’s body. It is found 
much more frequently in white or grey horses than in those of 
other colours, and mostly in aged ones, as the pages of this Journal 
will amply verify ; for whilst it records many cases of this disorder 
in white horses, we have few, if any, examples of its occurring in 
other coloured animals, although we are assured by French authors 
of respectability that it does affect them occasionally. 
The scientific arrangement of melanotic disorders has been un- 
dertaken by Bayle, Laennec, Breschet, and Carswell. The latter 
has divided this disease into true and spurious ; the first compre- 
hending those cases in which the deposit depends on the process of 
secretion within the animal body ; whilst the second depends upon 
the introduction of a carbonaceous body from without , or from the 
action of chemical agents on the blood, or from the stagnation of 
this fluid. 
With the spurious form the veterinary surgeon has, I imagine, 
