Symmers (141) and Oberndorfer (108) have already likened the influenzal
pulmonary complications to plague pneumonia, and it is quite possible
that others will find fundamental similarities with other fulminating,
inflammatory reactions. Inflammation, a series of processes manifested
after injury by a tissue which still retains its viability, is modified
by another important factor usually neglected; namely, the state of the
host. As a consequence, the inflammatory reaction might readily have
similar manifestations even though the primary exciting agents are
diverse. This has been amply demonstrated for many different reactive
processes, and still it may be considered as a challenge for those who
are of the opinion that specific bacterial agents necessarily produce
characteristic anatomical manifestations. Consider the state of
knowledge of the various reactions to the tubercle bacillus before this
microorganism was isolated; and then bear in mind that we are dealing
here with a disease whose causative agent, despite the present
uncertainty regarding its specific nature, produces a lesion that paves
the way for the invasion of the respiratory tract by many different
organisms. The extent of the reaction may depend upon the systemic
capacity to compensate, as well as upon the degree of primary damage in
a specific system of organs. Unquestionably, these two factors must take
their places in the balance, the opposite pan of which contains the one
or the other secondary bacillary invader.
[Illustration:
FIG. XXXVIII. THE UPPER ILLUSTRATION, AUTOPSY NO. 116, SHOWS A FRESH,
FIBRINOPURULENT PLEURAL EXUDATE. THE PLEURAL LINING CELLS ARE
SWOLLEN AND CONSPICUOUS. THE LOWER ILLUSTRATION, AUTOPSY NO. 100,
SHOWS ANOTHER AND LATER TYPE. THE ELEMENTS OF THE EXUDATE HAVE
DISINTEGRATED TO FORM A MUCILAGINOUS MASS. COMPARE FIGURE XXXVII.
]
[Illustration:
FIG. XLI. AUTOPSY NO. 140. IS A LOW POWER DRAWING OF THE
CHARACTERISTIC LUNG IN THE MORE CHRONIC STAGE OF THIS DISEASE.
NECROTIZING AND ORGANIZING BRONCHIOLITIS AND PERIBRONCHIOLITIS ARE
ASSOCIATED WITH AN ORGANIZATION OF THE EXUDATE IN THE ALVEOLI. THE
ORGANIZATION PROCESS IS SOMEWHAT OBSCURED BY THE EDEMA. COMPARE
FIGURES XI, XXXIX, XI, AND XLIV.
]
[Illustration:
FIG. XXXIX. AUTOPSY NO. 140. RIGHT LUNG. THE HISTOLOGY OF THE
PULMONARY CHANGES IN THIS CASE IS ILLUSTRATED IN FIGURES XI, XLI,
AND XLIV. THE NECROTIZING PERIBRONCHIAL FOCI STAND OUT PROMINENTLY
AND THE ORGANIZATION OF THE EXUDATE IN THE SURROUNDING ALVEOLI IS
ALSO DISTINCTLY SEEN IN THE ABOVE FIGURE.
]
Scientific medicine has reached that evolutionary period where, in
addition to the specific infecting microorganism, associated etiological
factors find an important place in the interpretation of a disease. More
and more attention is being directed toward the latter factors and the
rôle they play in respiratory infections. Many different factors open
the pulmonary portal for organisms and, in this way, terminate by a
serious respiratory inflammatory complication what otherwise might have
been a relatively mild disease. In the past two years this has been
demonstrated for measles.
For the above reasons, not only the immediate action but the
complications and sequelæ, too, of the inhalation of irritating gases by
normal healthy animals, emphasize themselves as a framework for a more
comprehensive interpretation of respiratory disease in general.