290 
A. LIAUTARD. 
In both cases it has the aspect of a blank, homogeneous sub¬ 
stance, sometimes grayish, ordinarily firm in consistency. The 
coloring matter which constitute them is soluble slowly in water 
and alcohol,, and colors these fluids when kept in them. 
Melanotic tumors have a natural tendency to increase in size 
by additions to the primitive nucleus; and once at a certain di¬ 
mension, they remain stationary. In horses they may assume 
enormous size, such as 30, 40, and even 50 pounds, but most 
ordinarily they remain small and no bigger than a hazel nut, or 
an apple, or even smaller, such as a pea, in which case they are 
found around the glands. The tumors may remain isolated or 
collected in large numbers, or found in all the organism, as in 
melanotic diathesis. 
Melanotic tumors do not always present themselves under the 
solid form which were found in this animal, especially when they 
assume the largest size, as the one found in the kidney and left 
lung. They are susceptible of softening, and become trans¬ 
formed either in part or in lots, in a kind of pulp or mud, which 
afterward ulcerate, throw out a dark, reddish liquid and leave 
ulcerated surfaces, sometimes called melanotic cancer, which then 
assumes an ugly appearance, very rebel to cicatrization, but 
rarely increasing in size. Virchow, placing them amongst the 
sarcoma, classifies the melanotic tumors under three separate 
groups : the simple melanoma, the melano sarcoma, and the 
melano carcinoma, and thus, admitting the possibility that there 
may exist true mixed forms of sarcoma and of carcinoma , or of 
tumors which may contain sarcomatous and carcinomatous ele¬ 
ments, we have an explanation of the possibility of the soften¬ 
ing of these growths, and of the malignity which accompanies, 
very often, their development—a point of great importance, and 
which must not be overlooked in the prognosis of these tumors. 
Such, especially, prove to be the case in this horse, for which a 
fatal termination was predicted when the first tumor was removed. 
The pigmentary infiltration* is admitted as the cause of 
the pathologico-histological alteration, that is an infiltration 
of coloring substance, of pigment in the tissues, which pigment 
*P’Arboral Dictionary, by Zundel. 
