12 
HEMOLYMPH NODES OF THE SHEEP 
or months of immersion it was found that both the black and the suc- 
ceeding gray color had completely disappeared, so that the tissue had the 
customary gray color characteristic of lymph nodes or of lymphatic tissue 
fixed in pure alcohol. This change in color occurred even if the alcohol, 
at the time when the tissue had lost the black color which was acquired 
through exposure to hydrogen sulphide, still contained hydrogen sul- 
phide in considerable quantity. Sometimes the alcoholic solution con- 
tained a small quantity of a dull black deposit after the nodes had lost the 
black color. This deposit or precipitate, which appeared only after weeks 
of immersion, was finely granular, and quickly sank to the bottom after 
shaking. 
The action of hydrogen sulphide was comparable to that of oxygen, 
then, in that its penetration was merely a superficial one, though the 
color change was apparently more rapid in the case of exposure to hydro- 
gen sulphide than to pure oxygen. This was true, both when a change 
from dark venous to red, or from a sulphide-produced black to a green 
color, was concerned; and it may be possible, as has been suggested, 
that the jet-black color of nodes, occasionally found post-mortem in sheep, 
may be due to the action of hydrogen sulphide formed in decomposi- 
tion ( ?) or from other tissue changes. 
In writing of the color changes following exposure to hydrogen sul- 
phide, Warthin [36] stated that "The important point is the fact that In 
the hemolymph nodes there may be such a quantity of iron-containing 
pigment that these nodes may take up hydrogen sulphide and become 
grayish or black in color, while the spleen remains unchanged." (The 
italics are the writer's.) Warthin further stated that the combination 
of hydrogen sulphide and iron is probably the cause of pseudo-melanosis, 
and added in a footnote that "The exposure of hemolymph nodes ob- 
tained from cattle and sheep produced results exactly like the autopsy 
findings in the above cases. The nodes quickly became discolored, some 
becoming uniformly grayish-black or brownish-black, others becoming 
spotted or streaked. The discoloration thus produced lasted for a longer 
time than that seen in human autopsy cases." The color changes re- 
ported by Warthin have been confirmed only as far as gross appearances 
are concerned, for frequent microscopical examination of nodes which 
had turned black spontaneously or upon exposure, never revealed a pic- 
ture of pseudo-melanosis, nor was a single test for iron in either the 
ferrous or ferric forms ever positive. But I am well aware that these 
tests may not be relied upon with certainty, and, moreover, that the iron 
may be in the organic form and hence nevertheless present. Consequent- 
