448 Pneumonia 



"ring type" is regarded as characteristic and enables the organism 

 to be separated without difl&culty from the streptococcus. 



Gelatia Punctures. — In gelatin puncture cultures, made with 

 IS instead of the usual lo per cent, of gelatin, the growth takes 

 place along the entire puncture in the form of minute whitish gran- 

 ules distinctly separated from one another. The growth in gelatin 

 is always meager. The medium is not liquefied. 



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

 the growth consists of minute, transparent, semi-confluent, colorless, 

 dewdrop-like colonies. The medium is not liquefied. Upon glycerin 

 agar-agar the growth is more luxuriant. The addition of a very 

 small percentage of blood-serum facilitates growth. 



Bouillon. — In bouillon the organisms grow well, slightly clouding 

 the medium. With the death of the organisms and their sedimenta- 

 tion, the medium clears again after a few days. 



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. — The organism usually dies after a few days of 

 artificial cultivation, and so must be transplanted every three or 

 four days. In rabbit's blood, in sealed tub^s kept cold, it can some- 

 times be kept alive for several weeks. Hiss and Zinsserf find that 

 when the organism is planted in " calcium-carbonate-inf usion broth" 

 and kept in the ice-chest, the cultures often remain alive for several 

 months. Bordoni-Uffreduzzif 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 nine- 

 teen to ninety-five days. Direct sunlight destroyed their virulence 

 in twelve hours. Guarniere§ found that dried blood containing 

 pneumococci remained virulent for months. 



The pneumococcus is destroyed in ten minutes by a temperature 

 of S2°C. It is highly sensitive to all disinfectants, weak solutions 

 quickly killing it. 



Metabolic Products. — Hiss|| found that the pneumococcus pro- 

 duces acid from monosaccharids, disaccharids, and such complex 

 saccharids as dextrin, glycogen, starch, and inulin. The fermenta- 

 tion of inulin by pneumococci is a most important means of 

 differentiating it from streptococci. 



Toxic Products. — Nothing definite is known about the metabolic 

 toxic products of the pneumococcus. 



Auld** found that if a thin layer of prepared chalk were placed 



* Ortmann asserts that the pneumococcus can be grown on potato at 37°C., 

 but this is not generally admitted. The usual acid reaction of potato makes 

 it an unsuitable culture-medium. 



t Loc. cii. 



t "Arch. p. 1. Sc. Med.," 1891, xv. 



§ "Atti della R. Acad. Med. di Roma," 1888, iv. 



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

 ** "Brit. Med. Jour.," Jan. 20, 1900. 



