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lung tissue is a difficult subject and so far an extremely unsatisfactory one. primary plague pneumonia, the B. pestis may be found in the blood stream. The condition is not septicemia. There is no evidence of the multiplication of the organism. Before death, on the other hand, similar to what occurs in other diseases, the blood swarms with the causal agents of the disease. Primary plague pneumonia would appear therefore to be something entirely different to the other form, presently to be described. In my opinion, it is the only true form of pneumonia (strictu sensu) found in plague. All other consolidations of lung tissue occurring during an attack of plague do not appear from my investi- gations to be pneumonias as we at present understand, but of a very different nature.
The second type of pneumonia, or what would better be termed, areas of consolidated lung issue, would appear to be distinct from primary pneumonic plague. In fact my own researches seem to show, that such areas of consolidation are in reality not areas of pneumonia. The type of pathological change met with is not comparable to true pneumonia. It is not definitely acutely fibrinous, or acutely catarrhal in type and would not appear to pass through the definite series of changes usually found in the now well recognised pneumonic diseases of the lung. The areas of consolidated lung tissue in this second type, are usually mul- tiple. Rarely they are single in the lung. They vary in size and distribution. Neither a lobular or lobar distribution is met with. They occur erratically. They occur as frequently subpleural as in the central lung tissue. The solid areas appear largely composed of extravasated blood in and around portions of the lung. Indefinite numbers of alveoli are included in the mass. There is not much evidence of participation of the actual cells, wall of the alveoli, and included connective tissue in the production of the lesion. The areas appear to increase iu size by peripheral extension of the hæmorrhagic infiltration. The more centrally situated areas apparently undergo necrosis.
I am inclined to the opinion that these so called secondary pneumonias, or the areas of consolidation of the lung, are in reality instances of what is known as pulmonary apoplexy or infarction. This is all the more likely when we remember that the action of the plague virus is severe on the circulatory apparatus inducing degeneration of the vessel walls, with the occurrence of multiple hæmorrhagic
extravasations.
This form of pest pneumonia, as it is called, is the result of blood infection. My researches in regard to this point are in accordance with those of WILM and the conceptions of GAFFKY.
In support of the foregoing, the occurrence of infective emboli with the production of metastaxis is well known in plague.
In such cases plague bacilli are present in hoards in the sputum.
It may be difficult in the absence of any definite previous history of the patient to say clinically, what particular type of consolidation is present.
Such areas of consolidation in the lung, account for many cases returned as plague pneumonia. It may set in during the early stages of the disease and be regarded as true pneumonic plague. Clinically, therefore, a diagnosis between primary pneumonic plague and these consolidated areas in the lung, may be almost impossible. Post-mortem, however, the anatomical relations of the pathological process determine the exact nature of the disease.
Such cases of so called pneumonia as a type of septicemic plague, would not appear to be so lethal as cases of primary pneumonic plague.
The bronchial glands are occasionally enlarged. Petechia may be found present. The mediastinal glands show practically the same. Both series are usually deeply pigmented. (Edema is another factor common to both. In one case in which multiple buboes were present, a distinct bubonic like mass was found in and around the superior mediastinal lymphatic glands. Vide Casé No. VII.
Lastly the thymus gland in children is often much enlarged and congested. Petechia may be found scattered throughout its substance. The normal milky Huid of the organ is much increased in amount, and must not be mistaken for pus which it resembles.