Report on the Pathological Anatomy of Fleuro-pneumonia. 187 
Black Consolidation. — The third form of consolidation to 
which I wish to call attention is generally found in well de- 
veloped cases of pleuro-pneumonia, though it is more frequently 
wanting than either of the preceding forms. Its appearance 
contrasts most strikingly with the changes hitherto mentioned, 
and it appears to differ from them also in its mode of produc- 
tion. It is at once distinguished from all other kinds of morbid 
change by its colour, which looks nearly black, so intensely 
dark is the red of the lobular tissue. From its cut surface a 
deep red fluid escapes, which stains all the paler structures dark 
crimson. 
The shape of this form of lesion is always that of a distinct 
cone, the apex of which points to the root of the lung, and its 
base to the pleura. Its boundary is invariably sharply marked 
off from the neighbouring diseased tissue, in the midst of which 
this dark part always lies. The lobular tissue is the only part 
which has the dark colour, the interlobular spaces being as pale 
as in the other forms of consolidation. The pale yellow of the 
interlobular spaces is exceedingly striking in this black part, 
and also forms a clear trenchant boundary to it. It is easy to 
satisfy oneself that the extent of this lesion corresponds accu- 
rately to that of a vascular territory. Sometimes an entire 
district supplied by a good-sized vessel is in this condition. 
In other cases several small territories are engorged, in which 
case they commonly all belong to the one district which receives 
its blood supply from the same main branch. 
The extent of this lesion is seldom so great as that of either 
of those already described, but its weight and density exceed 
those of any other form. The amount of swelling which accom- 
panies it is also very great, so that when a very prominent knob 
projects over the surface of the lung, and is covered with very 
intense pleurisy, one may safely predict that, on section, it will 
prove to be the base of a cone of this black marbling. It is 
invariably associated with very intense and acute pleurisy, which 
often gives one the impression of having commenced at this 
point, and spread thence over the serous membrane. 
The microscope shows the minutest vessels of the tissue to be 
intensely engorged. Even in those parts where the blackness 
has not reached its height, all the blood-vessels are tightly 
packed with blood discs, which are so pressed together as to 
form a continuous line of facetted corpuscles looking like a 
solid injection. The fluid part of the blood seems to have 
escaped from the vessels and left the solid parts alone in the 
swollen and tortuous capillaries. In the very black part, en- 
gorgement does not adequately express the state of affairs. Here 
the vessels have given Avay, and the blood-discs have escaped 
