204 THE MIOROSCOPE. 
ducts. It has never yet been possible for me to demonstrate a 
deposit of coal dust within Kupfer’s star-cells of the liver. 
IN THE KIDNEYS. 
The deposit of anthracotic pigment in the kidneys is of by no 
means frequent occurrence, although it may exist abundantly in the 
liver and spleen. I was able, however, in one single case to discover 
it deposited, although scantily, within an atrophied glomerulus. 
I think I am able to explain this by the fact that the kidneys are 
not only very abundantly supplied with blood, but that the blood in 
them changes very rapidly. In the periportal and mesenteric- 
lymphatic glands the anthracotic pigment is led by way of the 
perivascular-lymphatic ducts; which fact may be determined, 
because the capsule of the lymphatic glands and the peripheric 
lymphatic ducts are found laden with it. 
This black fine-grained pigment is not to be confused with 
gall pigment (bilirubin); it might more easily be confused with 
iron-pigment, micrococci, fatty degeneration of the epithelium cells, 
or with the so-called cells of fat particles (Gluge’s corpuscles), or 
finally with the putrid products of the epithelium. 
The iron pigment as it is found in pernicious anzmia, I have 
discovered either by ammonium sulphate (Schwefel ammonium) or — 
still better with ferrocyanide of potassium, and diluted muriatic acid. 
The latter means is preferable, since by its use the microscopical - 
sections have a very intense shade of dark-greenish blue, even 
microscopically; and it may be seen macroscopically that the iron 
pigment is colored distinctly green or light blue. In order to pro- 
duce lasting and beautiful preparations the following is the best 
method: Allow the sections to lie from 8 to 10 minutes in Ranvier’s 
picro-carmine, then wash them well in distilled water; next place 
them for 5 or 10 minutes in ferrocyanide of potash, then for a few 
minutes in diluted muriatic acid; wash again; dehydrate in alcohol 
absolute, clear in origanum or bergamot oil and embed in xylol, 
Canada balsam or damarlac. If the cuttings are placed in 
glycerin the iron pigment, very quickly (within three weeks), loses 
the blue-green shade and it is then no longer possible to recognize 
iron pigment as such, until the cuttings have been again successively 
treated with ferrocyanide of potash and diluted muriatic acid. 
The differential diagnosis between coal-dust metastases and 
micrococci is by no means easy. Both are finely grained and 
black (brownish black). 
(TO BE CONTINUED.) 
