OCCURRENCE OF CAUSATIVE AGENTS. 145 



type etiologically, but is a mixed form, the crisis does not 

 appear. On the whole, however, there are no fixed rules 

 for these mixed types. They render impossible the clinical 

 diagnosis with regard to the causative agent in the indi- 

 vidual case. 



5. Influenza-pneumonia is associated with the presence 

 of the influenza-bacillus, partly in pure culture, 'and partly 

 together with streptococci or pneumococci. 



6. The pneumonia complicating tuberculosis in the form 

 of caseous pneumonia may be due to the tubercle-bacillus 

 exclusively. On the other hand, pneumonia dependent 

 upon streptococci, pneumococci, and influenza-bacilli is, 

 however, not at all uncommon in tuberculous lungs. 

 When pneumococci take part in the morbid process, the 

 clinical picture assumes the peculiar characters that have 

 been described, and are indicative of an acute severe infec- 

 tion. 



7. The pneumonia complicating other infectious diseases is 

 less commonly due to the cause of those diseases as, for 

 instance, typhoid pneumonia due to typhoid-bacilli and 

 more commonly to the organisms usually causative of in- 

 flammation. The pneumonia that occurs in the sequence 

 of diseases of the abdominal organs is often associated with 

 the presence of the bacterium coli as, for instance, the 

 bronchopneumonia not rarely observed in connection with 

 incarcerated hernia. 



The bacteriologic diagnosis can be made from exam- 

 ination of the sputum, but the procedure of Koch, as de- 

 scribed by Kitasato, for the culture of tubercle-bacilli 

 directly from the sputum must be observed that is, the 

 mass of sputum must be thoroughly rinsed in dishes with 

 sterilized water, in order to remove the large number of 

 bacteria that have been added from the pharynx and the 

 mouth. Then a flake is isolated from the interior of the 

 mass, and this is smeared several times upon an agar-plate 

 or upon several glycerin-agar tubes in slants ; that which is 

 left is examined microscopically. 



Frequently direct puncture of the diseased lung has been 

 made with a thoroughly sterilized hypodermic syringe, 

 and a few drops of the exudate are obtained ; and these are 

 treated bacteriologically in the manner described. This 

 procedure perfect asepsis being observed need not occa- 

 sion the slightest concern, as it is often practised involun- 

 10 



