448 Pneumonia 



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

 to be separated without difficulty from the streptococcus. 



Gelatin Punctures. In gelatin puncture cultures, made 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 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 tubes 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-infusion broth" 

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

 months. Bordoni-UffreduzziJ 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 52C. 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 37C., 

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

 it an unsuitable culture-medium. 



t LOG. cit. 



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

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

 "Jour. Exp. Med.," vn, No. 5, Aug. 25, 1905. 

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



