THE PNEUMOCOCCUS AND PNEUMONIA 455 



exceeding 0.5 to 1 c.c. He found, furthermore, a striking parallelism 

 between the degree of toxicity and the virulence of the extracted cul- 

 ture. Cole, 55 too, in recent studies, inclines to the belief that the 

 poisons of the pneumococcus are in the nature of endotoxins and has 

 produced toxic substances by salt solution and bile extraction of the 

 organisms. 



Cole 56 states that when the cells of pneumococci are dissolved with 

 bile salts the solution becomes hemolytic and toxic. This hemolytic 

 substance is easily destroyed by heat, by tryptic digestion, and is 

 partially lost in nitration through Berkefeld niters. He believes that 

 there is some relationship between the virulence of the organisms and 

 these substances. An interesting fact, furthermore, is that the choles- 

 trin inhibits such toxic effects, but anti-pneumococcus serum is only 

 partially effective. , Cole differentiates this endocellular hemotoxin 

 from another substance that converts hemoglobin into methemo- 

 globin. The latter substance is produced only by the living cells, and 

 depends upon the presence of oxygen. 



In addition to these substances, there are very soluble materials 

 that appear in culture media in which the pneumococcus is grown, 

 during the life of the organisms, and which can be detected by specific 

 precipitin reactions. These substances, as we shall see, have been 

 found by Avery and Dochez 57 to be present in the blood and urine of 

 pneumonia patients. It is questionable whether or not they exert 

 toxic action in the infected body. 



Virulence and Pathogenicity. The virulence of pneumococci is 

 subject to much variation, depending upon the length of time during 

 which it has been cultivated. It has been mentioned above that 

 under conditions such as those prevailing in dried sputum or blood 

 the virulence of pneumococci may be preserved for several weeks. 

 Ordinarily, the virulence diminishes as the cocci adapt themselves 

 to life upon artificial media. Upon media containing animal albumin, 

 such as ascitic fluid or blood agar, this attenuation is less rapid than 

 upon the simple meat-infusion preparations. 



The maintenance of virulence, according to Kirkbride, 58 is greatly 

 aided by making transfers from broth to broth at intervals not 



55 Cole, Harvey Lecture, N. Y., Dec., 1913. 



56 Cote, Jour, of Exper. Med., 16, 1912, 644. 



"Avery and Doclicz, Proc. Soc. Exper. Med. and Biol., 14, 1016, 126. 

 M Kirldride, Paper read before the Amer. Assoc. Pathol. and Bacter., New 

 York, April, 1917. 



