FUNGI AND MODERN AFFAIRS — RAMSBOTTOM 323 



To understand the magnitude of work of this kind one has to take 

 into consideration that in a given species there are strains some of 

 which are more active, some less ; further, that the results differ accord- 

 ing to the chemical constitution of the medium and the physical condi- 

 tions of growth. 



Ever since fungi and bacteria were grown on artificial media, it has 

 been observed that in mixed cultures one organism may have no 

 apparent effect on the growth of the other, or it may influence it either 

 favorably or unfavorably. This favorable effect (synergism) may be 

 considered as an aspect of symbiosis; the unfavorable (antagonism) as 

 an aspect of the struggle for existence. 



Antagonism is gradually becoming recognized as a factor in plant 

 disease. The fungi which abound in the soil include some species 

 which are able to become parasites and cause destructive root rots. 

 Chemical and physical conditions of the soil determine the amount 

 of a given species, but they also act on the other fungi present, one or 

 more of which may have an antagonistic reaction toward the parasite. 

 Thus the mold Trichoderma viride, common in the soil, has an 

 antagonistic effect on the growth of the tree parasite Armillaria mellea. 



The phenomenon of antagonism has been brought strikingly to 

 public notice following an observation by A. Fleming in 1928. When 

 studying the growth of Staphylococcus on solid media in Petri dishes, 

 he noticed that the colonies underwent lysis in a zone surrounding a 

 growth of Penicillium which contaminated one of his cultures. He 

 grew the Penicillium in broth culture, and found that the filtrate was 

 some two or three times as effective as pure carbolic acid in stopping 

 the growth of Staphylococcus. 



For convenience the name "penicillin" was used in place of the rather 

 cumbersome phrase "mold-broth filtrate." Fleming showed that peni- 

 cillin had a specific action on certain bacteria (Staphylococcus, 

 Streptococcus, Pneumococcus, Gonococcus and the diphtheria bacil- 

 lus), but that others (B. coli and B. influenza) were not affected. 

 The first practical application of penicillin was the isolation of the 

 insensitive Pfeiffer's bacillus, which in the respiratory tract is usually 

 associated with organisms highly sensitive to penicillin. But Fleming 

 also stated that penicillin had no poisonous effect and that "it may 

 be an efficient antiseptic for application to, or injection with, areas 

 infected with penicillin-sensitive microbes." In 1931, he prophesied 

 that "it is quite likely that it, or a chemical of a similar nature, will 

 be used in the treatment of septic wounds." In the following year 

 Raistrick and his collaborators grew the Penicillium (which Thorn 

 identified as P. notatum) in a synthetic medium consisting solely of 

 glucose and inorganic salts, and defined the optimum conditions of 



