144 CLINICAL BACTERIOLOGY. 



cocci, and it is thus comprehensible why the symptoms dis- 

 appear abruptly with the occurrence of the crisis, while the 

 pneumonic infiltration remains ' unchanged. From these 

 facts it may be inferred that a toxic action on the part of the 

 pneumococci constituted a decisive element in the previous 

 clinical picture ; for, when the crisis at once obliterates the 

 disease, no change has been effected in its anatomic basis, 

 in the infiltrate itself; only the toxic activity of the pneu- 

 mococci has been withdrawn, and the manifestations, that 

 have just disappeared may, therefore, reasonably be referred 

 to that. 



Finally, it may be mentioned that true pneumonia has 

 been induced experimentally in favorable cases by inhalation 

 of pneumococci. Such experiments are usually attended 

 with difficulty, because the animals commonly employed 

 (rabbits, mice), which are so much more susceptible to the 

 pneumococcus than human beings, die, as a rule, in conse- 

 quence of the septicemic general infection, and localized 

 disease is induced in them with difficulty. 



2. Streptococcus-pneumonia corresponds with the clinical 

 picture of bronchopneumonia (cellular, catarrhal pneu- 

 monia). The infiltrate is only lobular, usually less dense, 

 and associated with less fibrin ; the sputum is mucopuru- 

 lent and not rusty ; the onset is not so pronounced ; the 

 course is more insidious and attended with remissions and 

 intermissions in the fever (so-called streptococcus-curve) ; 

 and, above all, the crisis is wanting. Some cases of strepto- 

 coccus-pneumonia are characterized by especial seventy 

 (pneumonie infectieuse of the French). The differentiation 

 of this variety is, however, not readily sustained, in the 

 first place because 



3. Staphylococcus-pneumonia, which is exceedingly un- 

 common as a single infection, resembles it absolutely ; and, 

 secondly, because of the occurrence. so frequently of 



4. Mixed forms of pneumonia, in which two or even three 

 of the bacteria named are found together. These forms of 

 the disease furnish clinically also a mixed picture that 

 occupies a position between croupous pneumonia and 

 bronchopneumonia. As a rule, the occurrence of blood- 

 streaked sputum or the temperature-curve, even when the 

 infiltrate is small, indicates the participation of pneumo- 

 cocci in the morbid process ; or, in a case of apparently 

 true croupous pneumonia, which, however, is not a pure 



