NONSPORE-FORMING BACTERIA 95 



pressed the growth of H elminthosforium sativum. It increased sporu- 

 lation of the fungus, inhibited or retarded spore germination, caused 

 abnormal hyphal development, and induced mutations in certain 

 strains of the fungus. The substance was thermostable and diffusible. It 

 passed through a Berkfeld filter, was absorbed by infusorial earth, 

 withstood freezing and desiccation, and did not deteriorate readily. It 

 was destroyed by alkalies but not by acids. It was inactivated or de- 

 stroyed, however, by certain fungi and bacteria (142). 



Various other spore-forming bacteria were found capable of inhibit- 

 ing the growth of bacteria, fungi, and other lower forms of life. In 

 many instances, only little is known of the nature of the active agent in- 

 volved. It is sufficient to illustrate this by an observation that B. h'lru- 

 denses, growing abundantly in the digestive fluids of leeches and con- 

 sidered as a symbiont of these animals, exerted a marked inhibitory 

 effect upon the growth of various bacteria and fungi (845). 



Antagonistic relations among entomogenous bacteria have been 

 demonstrated for the foul brood of the honeybee (441). This inter- 

 action between B. fopilliae and B. lentimorbus was believed to explain 

 the mutually exclusive development of the two types of milky disease 

 in Japanese beetle groups. 



NONSPORE-FORMING BACTERIA: PS. AERUGINOSA, 



Among the nonspore-forming bacteria, those belonging to the fluo- 

 rescent, green-pigment and red-pigment producing groups have prob- 

 ably received the greatest attention as antagonists. Bouchard (78) was 

 the first to report, in 1888, that the pyocyaneus organism {Ps. aerugi- 

 nosa) was antagonistic to the anthrax bacillus. It was soon found (131, 

 298) that when grown on artificial media, this organism affected bac- 

 teria, including E. tyfhosa, Pfeiferella mallei, V. comma, and Bac- 

 terium tyrogenes. The growth of staphylococci, micrococci, diplococci, 

 and spore-forming rods was also reduced. The antagonist inhibited its 

 own growth as well. 



These early observations were amply substantiated (Table 13). Ps. 

 aeruginosa was shown to be active against E. coli, M. tuberculosis, and 



