viil] MICROCOCCI 155 



middle ear ; in some cases of ulcerative endocarditis in which 

 the valves contain masses of this diplococcus ; in the bronchial 

 sputum in influenza, and in catarrhal bronchitis. This diplo- 

 coccus does not grow below 22° C. {i.e. not on ordinary 

 nutrient gelatine solidified) ; it grows well above 28° C., best 

 at 35° to 38° C. On Agar or on blood-serum it forms at 

 37° C, already after twenty-four hours, minute, translucent, 

 round colonies, which after two to three days appear raised, 

 moist-looking, whitish-grey, and round. In culture the 

 capsule around the diplococci is absent altogether or only 

 slightly indicated. 



On account of its presence in large numbers — sometimes 

 in pure culture — in the rusty sputum and in the blood-juice 

 of the lung in the stage of red hepatisation in the great 

 majority of cases of croupous pneumonia, prior to the height 

 of the disease, it must be assumed that it has an intimate 

 relation to the cause of this disease ; that it is not the only 

 cause of croupous pneumonia is shown by the fact that in 

 some cases only streptococci are present. In some epidemics 

 (Middlesbrough) a motile bacillus was found in pure 

 culture in the lung-juice in the red hepatised lung. But, 

 assuming with most pathologists that in the majority of 

 cases of genuine acute croupous pneumonia it is intimately 

 related to the causa vera, it is not easily seen why the same 

 microbe (the same in respect of morphological, cultural, and 

 physiological characters) should in one instance cause 

 croupous pneumonia, in another ulcerative endocarditis, in a 

 third peritonitis, and in a fourth suppuration of the middle 

 ear ; or why it should be found fairly abundantly in some 

 cases in the bronchial sputum (bronchitis, influenza) with- 

 out producing pneumonia. All this is obscure and un- 

 intelligible if the diplococcus pneumonia be considered as 

 the essential and sole cause of croupous pneumonia. 



