THE PNEUMOCOCCUS AND PNEUMONIA 449 



masses. The regularity with which this microorganism ferments 

 inulin medium, make it probable that it is more accurate to place it 

 with the group of pneumococci than with that of streptococci. 30 



Most of the organisms of this group show the common character- 

 istics of the pneumococci and are soluble in bile. Occasional strains, 

 such as one studied by Dochez and Gillespie, neither ferment inulin 

 nor are bile soluble. Rarely, too, does it cause hemolysis. From the 

 various studies carried out upon this group it must be concluded that 

 while perfectly distinct in its formation of a heavy mucoid colony and 

 capsulation, this group is more closely related to the pneumococci than 

 to the true streptococci. As would be expected from its capsulation, 

 its virulence is very powerful and serum reactions are not easily car- 

 ried out. A further discussion of the immune serum reactions with 

 this organism is included in this chapter, page 462. 



Resistance. On artificial media, the viability of the pneumo- 

 coccus is not great. Cultures upon agar or bouillon should be trans- 

 planted every third or fourth day, if the cultures are kept within an 

 incubator. In all media in which rapid acid formation takes place, 

 such as glucose media, the death of cultures may occur more rapidly. 

 In media containing albumin and of a proper reaction, preservation 

 for one or even two weeks is possible. The longer the particular race 

 has been kept upon artificial media, the more profuse is its growth, 

 and the greater its viability, both qualities going hand in hand with 

 diminishing parasitism. The length of life may be much increased by 

 preservation at low temperature, in the dark, and by the exclusion of 

 air. In calcium carbonate broth and kept in the ice-chest, cultures 

 may often remain alive for months. 



Neufeld has succeeded in keeping pneumococci alive and virulent, 

 by taking out the spleens of mice dead of pneumococcus infection and 

 preserving them in a Petri dish in a desiccator, in the dark and cold. 

 In this way, the organisms can be cultivated from the spleen, and will 

 be found virulent for longer periods than in culture media. The best 

 way to get such cultures back is by injecting a suspension of the 

 desiccated spleen, in broth, into a mouse, and recovering the pneumo- 

 coccus from the heart's blood. 



In sputum the viability of pneumococci seems to exceed that 

 observed in culture. The studies of (luariiieri, 37 Bordoni-Uffreduzzi, 38 



36 7/is-s, Jour. Exp., Mcd., 1905; Buergcr, Cent. f. Bakt., I, xli, 1906. 

 37 Guarnicri, Atta della R. Acad. Med. di Eoma iv, 1888. 

 88 Bordoni- Uffredussi, Arch. p. 1. Sc. med. xv, 1891. 



