Bauhaus-Universität Weimar

The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Todd, Robert Bentley
ears, however, to occur thus in the horse, 
n the associated form it is of very common 
occurrence, exhibiting itself in the form of 
points, spots, layers, or masses, in the sub¬ 
stance of natural textures or of adventitious 
products. In the latter condition it has more 
particularly excited attention, and been de¬ 
scribed under the titles of “ melanosis,” “me¬ 
lanotic tumour,” “melanoma,” &c. A full 
consideration of the modes of connection of 
cell-pigment with tumours will be found 
under the head of “ Melanoma” in the sec¬ 
tion “ Growths.” _ 
The substance we have just described being 
the only true black cell-figment, appears to 
be the only one legitimately falling under 
the present head ; but it is absolutely neces¬ 
sary (were it only for the purposes of diag¬ 
nosis) that we should briefly consider certain 
other causes (most ably investigated by Dr. 
Carswell) of black discolouration. These 
causes are, (a.) Alteration of the colouring 
matter of the blood ; (b.) Introduction of 
black-coloured substances from without. 
(a.) Alteration of hcematosine.— Stagnation 
and extravasation, and the action of certain 
chemical agents, are followed by this alteration. 
Stagnation produces its effect on the colour 
of the blood most distinctly in the capillary 
vessels, is more common in old than in young 
persons, and attends diseases of the heart and 
great vessels interfering with the circulation. 
Chronic inflammation is the most common 
immediate cause of the stagnation ; the intes¬ 
tinal canal and the lung the most common 
seats of the altered colour. In the intestinal 
canal, it is difficult (except by ascertaining the 
absence or presence of acid) to separate the 
effects of chemical agency from those of mere 
JExtravasated blood (occupying localities 
altogether removed from the influence of che¬ 
mical action not originating in itself, as, for 
example, in the common cellular membrane,) 
sometimes undergoes remarkable change of 
colour, becoming of a pitch black hue. The 
blackish and slaty discolouration frequently 
seen in points or patches under the mucous 
coat of the pelvis of the kidney, and also on 
the surface of the cortical substance, is evi¬ 
dently produced by infiltrated and altered 
blood. In these cases no pigment-cells are to 
be discovered, an amorphous granular mass 
exhibits itself, not materially differing in phy¬ 
sical characters (it is not, however, mixed 
with crystals and fragments of tissue,) from 
the colouring matter of gangrenous detritus. 
Chemical action is a frequent cause of black¬ 
ening of the blood. Blood poured into the 
stomach, and sometimes even if retained with¬ 
in its veins, is blackened by the gastric juice, 
either by direct contact or by imbibition. 
The effects of the acid secretion are precisely 
such as are producible by acids on blood re¬ 
moved from the body. The slaty discolour¬ 
ation of the anterior border of the liver, so 
common an appearance, is similarly explic¬ 
able ; the blood in its capillary texture being 
acted upon by hydro-sulphuric acid gas trans¬ 
uding through the adjacent intestines. 
(b.) Introduction of black coloured substances 
from without. — The lung (with its appen¬ 
dages) is the only organ in which this source 
of discolouration has been established. Pear¬ 
son * was the first to suggest, that inhaled 
carbonaceous matter was the true cause of 
the black lines and patches (following the 
course of the lymphatic vessels) often seen 
on the surface of the lungs, and of the well- 
known dark hue of the bronchial glands. That 
the colouring material was not of animal na¬ 
ture, he inferred from its being insoluble in 
nitric acid. Pearson’s view seemed to derive 
support from the well-known dark appearance 
of the morning expectoration of persons who 
habitually sit up much at night; and from the 
observation of Laennec, that the peasant^, 
but little prone to vigil, rarely expectorate 
dark sputa. 
But the most absolute collateral demon 
stration of Pearson’s correctness, is derived 
from the history of a peculiar disease to 
which colliers are subject. The lungs of in¬ 
dividuals affected with this disease become 
so thoroughly black ( Univ. Coll. Museum) 
as to resemble coal in colour ; and undergo 
gradual breaking up from irritative and ulcer¬ 
ative action.f Now the carbonaceous nature of 
this material, having been made matter of noto¬ 
riety by the experiments of numerous persons, 
it appeared natural to conclude that it was 
composed of coal dust inhaled in a state of 
extreme division. This notion was indeed 
espoused by Dr. J. C. Gregory j, but proved 
to be erroneous by Professor Graham), who 
showed that the material carried into the lung 
was none other than the soot or lamp-black 
formed by the combustion of the oil which 
the colliers use, suspended from their heads, 
as they work, in mines where the safety-lamp 
is not used. The constant exposure to the 
smoke of gunpowder employed for blasting 
has the same effect, though in a less degree. 
It remains for us to add, that we entertain 
no doubt of the black tint, present always 
more or less extensively in the lungs and 
bronchial glands of healthy persons (generally 
speaking, in the direct ratio of their ages), 
being in part due to inhaled sooty matter, 
but believe that it is likewise in part caused 
by alteration of the hæmatin of blood stag¬ 
nating in the capillary vessels. This opinion 
is, however, based on too small a number of 
micro-chemical examinations to lay claim to 
general admission. 
Finally, we may observe that the relation¬ 
ship of true melanic cell-pigment to the con¬ 
stituents of the blood, though made the 
subject of much dogmatical assertion, is alto¬ 
gether unknown. 
* Phil. Trans. 1813. 
f The precise anatomical characters of the disease 
it is, of course, beside our present purpose to enume¬ 
i Ed. Med. and Surg. Journal, No. 109. 
§ Ibid. Yol. 42. 
i 3


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