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The epiglottis usually hyperemic and edematous. The mucous membrane of the entire larynx, is found in a similar condition. The submucous connective tissue is usually edematous, and such continues from the larynx upwards to the pharynx and again to the capsule of the thyroid gland. The trachea and bronch are also found congested, and on the mucous membrane, a thick, greyish yellow secretion is found. This is often blood stained.
Plague bacilli can frequently be found in the secretion present on the mucous membrane. The smaller bronchi and bronchioles are usually much congested and oedematous. The pleural cavities frequently contain a small quantity of serous fluid. It may be blood stained. The pleura itself is usually in a condition of congestion, and petechiæ are almost always present in varying number.
The lungs, on opening the chest only partially collapse. They are usually vesicular throughout. On section, they are found congested, and dark, thick, tarry looking blood wells out of the cut ends of the pulmonary vessels. Edema of the lung tissue is frequently found. In cases associated with beri-beri this œdema is extreme, and on section, there flows from the cut surfaces a considerable amount of frothy, red serous fluid. The posterior parts of the lung tissue, is more solid and frequently sinks when placed in water. The condition is not pneumonia, but simply to the gravitation of blood to the most dependent parts of the organ.
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Occasionally one finds small areas of hemorrhage scattered throughout the lung tissue.
These can be seen previous to section of the organ. Many look like pulmonary apoplexy. Infarctions are also found. In plague, the occurrence of metastases in the lungs is common. Although plague pneumonia in its various forms is discussed freely, yet it is difficult even at the present day to find a clear account of the exact pathological processes at work in the production of such a condition. Mention is made in various treatises dealing with plague as to the presence of consolidated areas in the lung. These may be lobar or lobular. Pleurisy accompanies the process. The symptoms during life are those of pneu- monia and enorinous hoards of plague bacilli are found in the sputum.
In discussing the presence and mode of formation of pneumonic areas in the ungs in plague, we have to determine the following: The type or types of neumonia present, the distribution of the areas of consolidation in the lungs, the histological appearances of such consolidated areas, the part played by the plague bacillus in the production of the pneumonia, and the possibility of the origin of such a process being accelerated through the presence of other micro-organisations. These and other factors must be considered in regard to plague pneumonia.
So far as my experience goes, I believe that there exists two main forms of consolidation of lung tissue in plague.
One of these is undoubtedly a pneumonic process, namely, primary pneumonic laque. The second is a form of patchy consolidation occurring as a complication f ordinary septicemic plaque.
In the former the virus reaches the lung by way of the respiratory tract. In be latter, the infection is through the blood.
Pri-
Primary pneumonic plague is comparable to an influenzal pneumonia. The 3. pestis takes the same share in the production of this pneumonic plague, as the 3. influenzæ takes in the production of influenza pneumonia. Both these pneu-
onias are extremely fatal, primary plague pneumonia being especially so. ary plague pneumonia usually is lobar in distribution. It may be occasionally bular. The consolidation is complete, accompanied by lesions of the overlying leura and the production of large quantities of fibrin, in the meshes of which normous collections of red blood corpuscles are found, the condition is virtually hæmorrhage into the alveoli of a lobe or lobule of the lung. The intensity of the Iveolar changes are much greater than ever seen in pneumonia due to the neumococcus. So great are these changes produced by the growth of the B. estis in the alveoli, that a recovery is, in almost all cases, not to be entertained.
This form of plague pneumonia is not common in Hongkong.
The part played by other micro-organisms in its production is difficult to etermine. Pneumococci and streptococci are almost always present with the . pestis in the sputumn. The subject of mixed infection aud its action on the