MELAN^EMIA. 
291 
is the result of a chemical transformation of the liematine of the 
blood corpuscles, which by modern researches have proved to be 
of the same nature as the coloring matter of the blood. How¬ 
ever, this pigment of the melanosis does not differ from that 
which is, physiologically speaking, produced in the epithelium of 
the choroid of the eye, in the network of Malpighi of the skin, 
<fcc. According to Reindfleish, there is first a diffused imbibi¬ 
tion of the tissues by the coloring matter, then a period of granu¬ 
lar or crystalline precipitation of the pigmentary matter. This 
granular pigment is formed, as indicated by its name, of very 
small granulations, yellow, brown, or black, collected in small 
masses and mingling in larger and more homogeneous masses. 
When these granulations fill up the protophesma of a cell, the 
colorless nucleus is pushed aside, or surrounded by the pigment, 
and it seems that the pigmentary cell presents a round lacuna, or 
a hole. In the round cells, the nucleus soon becomes invisible, 
and then it remains a pigmented corpuscle, in which the external 
form of the cell is lost. Sometimes the walls of the cell disap¬ 
pear, and it is then that is formed the melanotic mass free, 
specially found in horses. 
Though the condition of development of melanoma are yet 
almost unknown, Bruckinueller says that they always form them¬ 
selves in the cellular tissue, especially the sub-cutaneous or sub- 
serous tissue. This was proved also in this post-mortem, where 
the principal growths were found under the peritoneum, between 
its layers and under the serous lining the thorax cavity, the 
pleura. But they are also frequently met in parenchymatous 
organs, in lymphatic glands, heart, liver, lungs, kidneys, and 
spleen. 
It is this formation* of melanosis in the cellular tissues, which 
explains how these tumors are observed in all the parts of the 
body, as well internally in viscera as externally on the skin and 
in the subcutaneous cellular tissue. External melanosis are often 
found in horses, round the anus, at the base of the tail, and round 
the vulva. First of small size, these productions increase and be¬ 
come as big as a pigeon’s egg. In growing they assume irreg- 
*£iuid<5l, 
