Toxic Products 333 



with 15 instead of the usual 10 per cent, of gelatin, the 

 growth takes place along the entire puncture in the 

 form of minute whitish granules distinctly separated from 

 one another. The growth in gelatin is always very meager. 



Agar-agar and Blood-serum. Upon agar-agar and 

 blood-serum the growth consists of minute, transparent, 

 semi-confluent, colorless, dew-drop-like colonies, which die 

 before attaining a size which permits of their being seen 

 without careful inspection. Upon glycerin agar-agar the 

 growth is more luxuriant. The addition of a very small 

 percentage of blood-serum greatly facilitates the growth. 



Bouillon. In bouillon the organisms grow well, slightly 

 clouding the medium. 



Milk. Milk is an appropriate culture medium, its casein 

 being coagulated. Alkaline litmus milk is slowly acidified. 



Potato. The pneumococcus does not grow upon potato.* 



Vital Resistance. Bordoni-Uffreduzzi found that when 

 pneumococci were dried in sputum attached to clothing, 

 and were exposed freely to the light and air, they retained 

 their virulence for rabbits for from nineteen to ninety-five 

 days. Direct sunlight destroyed their virulence in twelve 

 hours. Guarniere found that dried blood containing pneu- 

 mococci remained virulent for months. 



Metabolic Products. Hissf found that the pneumococcus 

 produces acid with ease from monosaccharids, disaccharids, 

 and such complex saccharids as dextrin, glycogen, starch, 

 and inulin. 



Toxic Products. Nothing definite is known about the 

 metabolic toxic products of the pneumococcus. That the 

 symptoms of pneumonia are not entirely dependent upon 

 the disturbance of respiration is clearly shown by the fact 

 that the patients suffer from high fever and have marked 

 leukocytosis with enlargement of the spleen. The cases in 

 which the cocci invade the blood are usually more serious 

 than those in which their operations are restricted to the 

 lung. 



The toxin must be purely or almost purely intracellular, 

 however, as filtered cultures are scarcely at all toxic. 



* Ortmann asserts that the pneumococcus can be grown on potato at 

 37 C., but this is not generally confirmed. The usual acid reaction of 

 the potato would indicate that it was a very unsuitable culture medium. 



t "Jour. Exp. Med.," vii. No. 5, Aug. 25, 1905. 



