336 BACTERIOLOGY. 



Apparently, a useful method of distinguishing' the Loffler bacil- 

 lus from the pseudo-diphtheria bacillus is that of Neisser. The cul- 

 tures are developed for 10-20 hours on the L6fiB.er's serum at a tem- 

 perature not exceeding 35°. The cover-glass preparations are treated 

 for 1-3 seconds with an acetic acid methylene blue solution. This 

 is prepared as follows: 1 g. of Griibler's methylene blue is dissolved in 

 20 c.c of 96 per cent, alcohol, and to this 950 c.c. of distilled water 

 and 50 cc of glacial acetic acid are added. The specimen is rinsed 

 in water, and then treated for 3-5 seconds with aqueous Bismarck 

 brown. The latter is made by dissolving 2 g. of vesuvin in 1 liter of 

 boiling water. By this process the isolated polar granules are ren- 

 dered manifest in the case of the true diphtheria bacillus, but are 

 not to be seen in the pseudo-diphtheria bacilli. According to Fraen- 

 kel, an organism which fails to show these double stained polar gran- 

 ules is not a true diphtheria bacillus. On the other hand, pseudo- 

 diphtheria bacilli may, though very rarely, show slight polar bodies. 

 In such cases the production of acidity in bouillon and the effect on 

 guinea-pigs should be tested. 



Pneumonia. 



The Diplococcus lanceolatus is of extreme interest be- 

 cause of its peculiar biological properties, and because of its 

 frequent occurrence in various inflammatory diseases. Thus, 

 it is by far the most common cause of croupous or fibrinous 

 pneumonia, and fully one-half of the cases of cerebro- 

 spinal meningitis are due to it. Many cases of broncho- 

 pneumonia are likewise ascribed to the Fraenkel diplo- 

 coccus. The lungs and the meninges are, therefore, espe- 

 cially suitable for its development. The serous surfaces, 

 moreover, furnish a favorable location and hence it is that 

 this diplococcus is a frequent cause of pleurisy, pericar- 

 ditis, endocarditis and peritonitis. It is, likewise, met with 

 in inflammation of the middle ear (otitis media), and in 

 abscesses. 



The fact that it is frequently present in the healthy 

 mouth, nose and throat, indicates that the natural resist- 

 ance of the body must be overcome or lowered before the 

 organism is capable of inducing a disease. Invasion may 

 occur through the blood or through the lymph spaces. 

 The virulence of the germ, the way in which it enters, and the 



