BIOLOGY OF PNEUMOCOCCUS 51 



to diffuse daylight. They concluded that the blood and proteins in 

 the sputum formed a protective coating for the cocci. Wood 1542 

 studied the longevity of Pneumococcus in sputum when subjected 

 to varying temperatures. In moist sputum, kept in the dark at 

 room temperature, the average life of Pneumococcus is eleven 

 days, while at 0° it is, as a rule, thirty-five days. When the spu- 

 tum is kept in strong light at room temperature the life span is less 

 than five days. In dried sputum Pneumococcus lives, on an aver- 

 age, thirty-five days in the dark, thirty days in diffuse daylight, 

 and less than four hours in sunlight. In powdered sputum, death is 

 a matter of a few hours. Pneumococci in sprayed, moist sputum 

 rarely survive for more than an hour, and often die in less time. 

 The material upon which the sprayed particles fall has little influ- 

 ence on the life of the organism. On the contrary, Emmerich 355 and 

 more recently Stillman, 1326 have demonstrated the longevity and 

 continued virulence of pneumococci in a dried condition. Stillman* 

 recovered viable organisms from pneumonic sputum dried in test 

 tubes and exposed for three months or more to diffuse daylight at 

 room temperature. Germano, 511 too, found pneumococci resistant 

 to drying, but the details of his experiments are lacking. Hintze 646 

 kept blood-agar cultures alive for thirty-two months by storage in 

 tubes stoppered with cotton plugs. For the purpose of keeping 

 pneumococci viable and virulent, Savino and Acuna 1220 placed the 

 blood of mice or rabbits infected with Pneumococcus in one arm of 

 an H tube with phosphoric anhydride in the other arm and then 

 sealed the tube after evacuating the air. 



The thermal death-point for Pneumococcus as given by Stern- 

 berg 1321 is 52° for ten minutes. 



For practical purposes, however, such as the maintenance of 

 virulent stock cultures or of other infectious pneumococcal mate- 

 rial, in addition to refrigeration of inoculated blood in sealed tubes 

 and the devices already described, the rapid drying of cultures, 

 infected organs, blood, or sputum presents many advantages. 



* Personal communication. 



