114 BACTERIAL ASSOCIATIONS 



up these divergent and variable results, I feel that they tend to confirm the inter- 

 pretation we have given. The results will depend on many factors such as the rela- 

 tive ability of each bacillus to attack the salts of the organic acids, the effect of al- 

 kaline reactions, and others. 



THE HEMOGLOBINOPHILIC GROUP 



The association of bacteria with the B. influenzae group has received unusual at- 

 tention. The discussion of this part of the subject, even briefly, would take all my 

 available space. I must merely observe that it has been studied from the earliest days 

 of the discovery of the B. influenzae and gives striking illustrations of the importance 

 of the subject. Many bacteria help the growth of B. influenzae on media, otherwise 

 inhibitory, such as human blood agar, but they have little or no effect on properly 

 heated blood agar. These beneficent bacteria are most variable in their characters, 

 and include many listed as highly antagonistic such as B. pyocyaneus, an organism 

 around whose antagonistic activity there has collected a comprehensive literature. 

 B. influenzae will grow on hemoglobin-free media in association with many bacteria, 

 although Putnam and Gay' and others were unsuccessful in doing this, and the im- 

 portance of this and the possible bearing it may have in infection have been repeated- 

 ly stressed. Eggerth^ was able to grow B. influenzae in plain broth within a collodion 

 sac immersed in cultures of staphylococcus, streptococcus, or pneumococcus and sug- 

 gested this method as useful for studying symbiosis of bacteria while keeping each 

 in pure culture. It would be of great interest to learn if toxin production may be 

 permanently increased by certain of these combinations. Certainly the virulence is 

 readily raised by mixed injections, as Yanagisawa,-5 Hudson" and others have shown. 

 I will not attempt to review the literature because this has been done by me^ and by 

 Kristensen.^ I do not believe there has been anything new on the fundamental ideas 

 of bacterial associations with B. influenzae since those reports. I cannot leave the 

 subject of influenza without mentioning the importance OHtsky and Gates,^ in a long 

 series of articles, have placed on the relationship between the B. pneumosintes and 

 secondary infections. I may say that their controls were quite inadequate to justify 

 the conclusion that this organism is more potent in encouraging secondary infections 

 than a host of others. 



B. ANTHRACIS 



In anthrax it has been repeatedly shown that combined injections frequently 

 prevent infection. I have found that guinea pigs did not die after large injections of 

 washings from soil contaminated months before by B. anthracis in the slaughterin;^ of 



' Putnam, J. J., and Gay, D. M.: /. Med. Research, 42, i. 1920. 



' Eggerth, A. H.: /. Biol. Chem., 48, 203. 1921. 



3 Yanagisawa, S.: Kilasato Arch. E.vper. Med., 3, 85. 1919. 



■I Hudson, N. P.: /. Infect. Dis., 34, 54. 1924. 



sHolman, W. L.: Studies on Epidemic Influenza, p. 161. University of Pittsburgh, 1919. 



'' Kristensen, M.: IlaemoglohinopltUic Bacteria. Copenhagen, 1922. (In English.) 



'Olitsky, P. K, and Gates, F.L.: J. A. M. A., 74, 1497. 1920; 78, 1020. 1922; 81, 744, 21 19. 1923; 

 /. Exper. Med., 33, 125, 361, 373, 713. 1921; 34, i. 1921; 35, i, 553, 813. 1922; 36, 501, 6S5. 1922; 

 37. 303- 1923- 



