* "Deutsch. med. Woehenschr.," 1882, p. 268.

We must also shortly describe another form, which was designated, both bacteriologically and pathologically, by Winkler as the most important and most frequent complication of influenza. It concerns a special class of pneumonic affections which the author described first in 1888 as "acute primary streptococcus pneumonia"-a pneumonia which, since that time, has persisted in Bonn. It is remarkable that whereas this pneumonia, before the influenza pandemic, occurred in particularly malignant endemics, "reminding one of typhus or septicemia," later, in the influenza period, when its similarity to influenza was astounding, it suddenly took on a milder character, and in the years 1893-1894 " these pneumonias suddenly became of short duration and not at all dangerous to life." Finkler thinks it likely that "in Bonn an endemic distribution of streptococci existed, so that before, during, and after influenza, streptococcus pneumonia became prevalent." In the influenza period there was in Bonn "a very remarkable epidemic, a mixed infection of influenza and acute primary streptococcus pneumonia."

According to Finkler, this primary streptococcus pneumonia has pathologically nothing in common "with croupous pneumonia," and it is not a bronchopneumonia, but occurs primarily in the lung, and is not necessarily preceded by bronchitis. It always arises in lobular, frequently multiple areas, which "only rarely give rise to pseudolobar forms of infiltration." "The cut surface of the lung is smooth, with no hepatization, but showing splenization." Microscopically, the infiltrated areas are "lobular areas showing the characters of an acute interstitial pneumonia, chiefly with a catarrhal exudation into the alveolar lumina, and but rarely accompanied by an admixture of fibrin; the alveoli are filled with fluid and with large and small epithelioid and round cells."

The lobular, catarrhal streptococcus pneumonia complicating influenza has been alluded to above. (See p. 611.) We emphasized the fact that in the course of a catarrhal pneumonia caused by the influenza bacillus streptococci might enter either simultaneously or secondarily, and finally even outnumber the influenza bacilli. The inflamed lung of influenza becomes the battlefield of various cocci, of which first one, and then the other, obtains the mastery. In a similar manner we may explain the fibrinous form of influenza pneumonia as a mixed or secondary infection with the Diplococcus lanceolatus.

The question concerning the primary or genuine streptococcus pneumonia (Finkler) is another matter. The confusion of this form with the streptococcus pneumonia depends upon mixed or secondary infections during the course of influenza, which has unnecessarily complicated a really simple question. This secondary streptococcus pneumonia is based upon sound pathologic or clinical data. Different, however, is the case with the primary form, which is supposed to occur as a nosologic entity, and to attack healthy individuals in a similar manner to a croupous pneumonia-suddenly with a rigor. In the course of time a marked change has taken place, during the prevalence of influenza, in this form of pneumonia-i. e., it has changed from an originally malignant to a benign and harmless affection. Clinically and bacteriologically this malignant form corresponds to the well known asthenic, typhoid or croupous pneumonia, whose atypical malignant character we have considered as due to a mixed streptococcal infection. (See p. 619.) But pathologically this primary streptococcus pneumonia is supposed to be of quite different nature, namely, an intense catarrhal or cellular pneumonia, which "has absolutely nothing to do with the croupous variety," and consequently has also nothing in common with our atypical croupous pneumonia, whose exudate is often poor in fibrin (flabby hepatization), and whose structure is not infrequently of the lobular variety.

Nevertheless, many statements of Finkler point to the close relationship of his streptococcus pneumonia with the atypical croupous form. Thus in one case the whole left lung within seventeen hours, and in another case the whole right side within twelve hours, became "rapidly" infiltrated and "splenizecl." The fact that on postmortem examination of such acute cases a granular surface was not found is easily explained by the short duration of the clinical course of the disease, which in the latter case existed only for twelve hours. The statement of Finkler that "rusty pneumonic sputa are by no means regularly found" signifies that such sputa, which are pathognomonic of the croupous form, were, at any rate, not uncommon.

For this "new class" of the primary streptococcus pneumonias the term "erysipelas of the lung," in use during the last century, has been proposed. In support of this designation the following points are brought forward: 1. "The pathologic character and the cellular nature of the inflammatory process," although this character is common to all catarrhal pneumonias. 2. "The marked disposition of continuous extension from lobule to lobule," which again is a peculiarity that is noticed in all bronchopneumonias and is by no means rare even in croupous pneumonia. 3. "The intense erysipelatous reddening and swelling of the trachea and bronchi," which also take place occasionally in all forms of pneumonia. 4. "That the disease is caused by the Streptococcus erysipelatis," but here again, to what confusion would it lead if we considered all processes in which streptococci were found as erysipelas? 5. "The character of the inflammation as an acute interstitial pneumonia"; in other places the inflammation is defined as "a predominantly cellular variety, with affection of the interstitial tissue."

Such interstitial processes, edematous swelling, granular infiltration, leukocytic accumulation in the interstices between the alveoli, as well as around the vessels and bronchi, are found in all forms of pneumonia, and especially in the catarrhal as well as in certain stages of croupous pneumonia.* The choice of the term "erysipelas of the lung" for the "new class of pneumonias" seemed to indicate that the most important pathologic characteristic of erysipelas, namely, the filling of the lymph channels with streptococci, would be found, but of this we nowhere find any mention. All that we read of is the occasional "filling of the larger lymph vessels with masses of coagulum."