THE MICROSCOPE, 201 
v v, ventral blood-vessel; n g, nerve ganglion; p e, peritoneal 
epithelium; s m, setal muscles. 
Fie. 2.—Highly magnified cross-section of wall of alimentary 
canal: cu, cuticle of inner surface; cp, columnar epithelium; / 6 v, 
blood vessels; c m, circular muscles; J m, longitudinal muscles; ch; 
chloragogue layer; p e, peritoneal epithelium. 
Fic. 3.—Transverse section of nerve ganglion: g f, giant fibers; 
m s, muscular sheath; 1 n, lateral nerve; n c, nerve cells; sn v, 
sub-neural blood vessel. 
Fic. 4.—Ovary: ov, ripe ovum; a, undeveloped ova; 0, ova not 
differentiated from other cells. 
Fie. 6.—Shows relation of musculature of seta to muscular 
layers of body wall, c. 
Fic. 7—Nephridium: f, funnel; c, ciliated portion; g, glandu- 
lar portion; m, muscular portion. 
Brotoetcat Laporatrory, CARLETON CoLLEGE, 
Northfield, Minn., May 1, 1889. 
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. 
F the process remains confined to the lymphatic gland and its 
capsule, calcification may result; even the entire gland, 
together with the capsule, becoming calcified in toto. These 
calcified masses may be conveyed by means of perforations into the 
air-passages and out of these to the exterior; or, they may cause an 
obstruction of the air-passages and so directly lead to death by suf- 
focation, or indirectly, by secondary broncho-pneumonia. In regard 
to this there occur in the literature on the subject a few inter- 
esting cases: An observation of Edwards was described in 
the ‘ Medico-chirurgical Transactions,” 1854, vol. 37, p. 151; 
a second case was published by Roth, ‘“ Correspondenzblatt 
fiir die Schweizer Aerzte,”’ Jahrgang XIV, 1884; the third was 
* Continued from page 170. 
