BIOLOGY OF PNEUMOCOCCUS 49 



Viability 



The factors already described, along with temperature condi- 

 tions, determine not only the speed and mass of growth but the 

 span of life of Pneumococcus. In highly buffered fluids such as 

 blood, blood serum, or media containing these body tissues, Pneu- 

 mococcus can be preserved alive and virulent for long periods of 

 time. Arkharow (1892) 17 found that blood from infected mice and 

 rabbits retained its virulence if kept in sealed tubes in the dark at 

 room temperature. Foa and Bordoni-Uffreduzzi (1888) 462 incu- 

 bated the blood of an infected rabbit for twenty-four hours and 

 then stored it in the dark in the cold. Vitality was preserved for 

 fifty to sixty days. Rymowitsch 1199 accidentally noted that hemo- 

 globin in the medium would conserve viability and virulence for an 

 equal length of time at 36° to 38°. Yourevitch 1566 proposed a 

 method, based on the protective action of blood and tissue, for 

 preserving pneumococci in latent culture. Blood is aspirated by a 

 pipette and expelled into the bottom of tubes of glucose or serum 

 broth, or a whole heart or fragments of clotted rabbit blood may 

 be added. After planting, the cultures are hermetically sealed and 

 kept in the ice-box. In such cultures both viability and virulence 

 remain unimpaired for several months. 



Romer 1155 preserved pneumococci by mixing the heart-blood of a 

 rabbit dead from pneumococcal infection with sterile saline solu- 

 tion and storing the infectious material in sealed tubes in a cool, 

 dark place. He maintained the virulence of the stock material by 

 weekly passage through rabbits. 



Washbourn, 1486 dissatisfied with these methods, preserved stock 

 cultures as long as fifty days by covering the growth on agar cul- 

 tures with a thin layer of rabbit blood. Gilbert and Fournier 513 

 kept strains viable for two months by simple inoculation in fluid, 

 defibrinated blood. The cocci still showed capsules and were viru- 

 lent for mice. Bezancon and Griffon 112 modified Gilbert and Four- 

 nier's procedure by injecting a proteose solution in dogs, then 

 mixing their blood with ascitic or pleuritic fluids before seeding 



