140 REVIEW— A TREATISE ON PATHOLOGICAL ANATOMY- 
the brain, although the latter in its healthy state presents in cer- 
tain parts a black colour which might be denominated natural 
melanosis. The lymphatic ganglions are frequently attacked by 
melanosis, and then often grow to an enormous size. It may 
exist alone in an organ, or be combined with other accidental pro- 
ductions. It is often the associate of scirrhus a id sometimes of 
tubercle. 
It may attack a greater or less number of organs at the same 
time. It has existed simultaneously in the subcutaneous and 
intermuscular cellular tissue, in the peritoneum, the pericardium, 
and the pleura, in the ovaries and the sternum, and in the bones of 
the cranium. It is observed at all ages. It occupied the whole 
of the superior lobe of the left lung in a girl only nine years old, 
and it is of too frequent occurrence in old men labouring under 
chronic pneumonia. 
It is not an affection peculiar to man. It has been most fre- 
quently observed in the horse, not, perhaps, because it is most 
frequent in him, but because he is the oftenest examined. The 
lymphatic ganglions are the parts that seem to be most subject to 
this affection. The submaxillary ones are often greatly indurated, 
increased in size, and of a black colour. M. Gohier, formerly vete- 
rinary professor at Lyons, found in the horse melanic masses in 
the parietes of the heart, in the lungs, the spleen, and even the 
spinal cord. Professor Rodet has found an induration of more 
than one-half of one of the parotid glands. In another he found a 
remarkable kind of melanosis in one of the eyes : the space usually 
occupied by the vitreous humour was filled with a fluid as black as 
Indian ink, in which floated equally black clots. The crystalline 
lens was of a deep yellow colour, and in some parts even brown. 
It is particularly in white or dapple-grey horses that this acci- 
dental production has been observed, as if the colouring matter, not 
being secreted in the integuments, was formed in a more or less 
modified state in the internal organs. This, however, is perhaps 
too hastily generalizing, for it has been found in horses of all 
colours. 
It has also been found in the dog, the cat, the rabbit, the mouse, 
and the rat. 
The symptoms to which this affection gives rise have nothing 
peculiar about them. They appear to depend, 1 . On the chronic 
irritation that so often accompanies it, whether as cause or effect. 
2. On the simultaneous existence of other accidental productions. 
3. On the uneasiness mechanically produced by its presence in 
more or less voluminous masses, from its compressing like any 
foreign body the parenchyma of the organ in which it is developed. 
