The incrustations of fibrine around the blood vessels can be replaced
in later stages by thick fibrillae of connective tissue; this. however, does
not seem to occur frequently. More usually dense crowds of leucocytes
take the place of the fibrine, which in turn undergo regressive metamor-
phoses: karvorhexis, karyolysis, and protoplasmolysis change the whole
finely granular mass into untingable flakes of granules, which are in part
resorbed and carried away by emigrant leucocytes, and a regenerative
process sets in, by which the defect is replaced by fibrillae of connective
tissue.
Should a portion remain behind as detritus, it fills fissure between
the sequester formed as just described and the surrounding layer of
connective tissue. The connective tissue of the capsule usually merges
into that of the interstities; in the immediate vicinity of the sequesters
the characteristic alterations of the lymph vessels with the typical incrus-
tations of fibrine are however demonstrable.
Such conditions appear regularly in chronic cases of pleuro-
pneumonia, and in the light of what has been said already can well serve
as basis for diagnosis.
The walls of the lymph vessels merit special attention, for we have
to decide whether we have to do with a lymphangitis or not. This
question is the more important, as Csokor is of the opinion that it is a
productive meso and periarteriitis of the capillaries of the interstitial tissue,
of which the enormous stasis in the lymphatic vessels is a consequence.
Perfectly fresh foci from the lungs would be most suitable for the study
of this problem; hut as such stages are rare we are obliged to have
recourse to foci derived from other tissues, and to make our deductions
by comparative anatomical methods.
