THE MICROSCOPE. 167 
action of acids. This makes the process somewhat alternate. First 
a dissolving out of the lime-salts, then loosening and breaking up of 
the organic material, etc. 
At first the process is slow, but as advance is made, the cavity 
becoming larger, its capacity for holding liquids and decomposing 
particles of food is greater; the inner part of the tooth containing 
less and less earthy material, the process becomes more and more 
rapid until the pulp is reached, which, not being able to withstand 
the sudden changes of temperature it is now subjected to, soon dies. 
CONCERNING THE DIFFERENTIATION OF BLACK PIG- 
MENT IN THE LIVER, SPLEEN AND KIDNEYS, 
FROM COAL-DUST DEPOSITS.* 
FREDERICK GAERTNER, 
A. M., M. D., UNIVERSITY OF STRASSBURG, GERMANY; M.D., ST. LOUIS MED. COLLEGE; A. B., MOUND 
CITY COLLEGE, ST. LOUIS: CERTIFICATE ILLINOIS STATE BOARD OF HEALTH; CERTIFI- 
CATE OF ENDORSEMENT FROM UNIVERSITY OF PENNSYLVANIA; MEMBER IRON CITY 
MICROSCOPICAL SOCIETY AND OF THE AMERICAN SOCIETY OF MICROSCOP- 
ISTS; MEMBER GERMAN SOCIETY PHYSICIANS AND SURGEONS OF 
BERLIN; HON. MEMBER OF PHYSICIANS AND SURGEONS 
OF VIENNA; CORRESPONDING PHYSICIAN TO THE 
STRASSBURG PATHOLOGICAL SOCIETY, 
ETC., ETC. 
NAUFF asserts (Virchow’s Archiv., Vol. XXXIX, page 442, 
1867) that in animals confined in the smoke chamber 
for a time, the inhaled coal-dust had penetrated to the extrem- 
ities of the breathing organs; further, that the pigment for the 
most part adhered to the cellular elements, but free pigment had 
also lodged in the alveoli. These cellular elements were partly free, 
partly more or less detached, or fixed to the walls. The filling 
of the cells with coal-dust was, as a rule, incomplete. The same 
formations were also found lodged in the parenchyma beneath the 
surface of the alveoli. A narrow but distinctly visible strip of 
colorless lung tissue separated the lumen of the alveoli from the 
stratum containing the coal. The black particles lay either 
scattered and seemingly without definite order, or formed more or 
less connected lines. The arrangement of the coal particles in 
ramifying lines appeared still more distinctly on the surface of the 
lungs. From these manifold branching lines, connecting chains 
proceeded, so that the whole presented the appearance of a vascular 
system. And thus the design of the injected lymphatic vessels was 
traced by the coal-deposit. When an animal had been exposed to 
* Continued from page 131. 
