150 FUNGI AS ANTAGONISTS 



-pamfeana, for example, normally does not form any perithecia in cul- 

 ture but is able to do so in the presence of Basis-porium gallarum or 

 Fusarium monilijorme. This effect was ascribed to a special substance 

 that resists heating at i io° C. Different fungi have a special influence 

 on the germination of spores of various ascomycetes and of other fungi 

 (28, 776), these effects being characteristic of the antagonists. 



The edible mushroom Psalliota camfestris exerts a definite antago- 

 nism against the parasitic fungus Mycogone (135). This phenomenon 

 has been looked upon as a case of antibody formation. Species of Fusch 

 rium are able to antagonize the mushroom fungus 5 however, an actively 

 growing culture of the latter may become antagonistic to the former 

 (1026). In the destruction of paper pulp by fungi, a marked antago- 

 nism was shown (341) to take place between different organisms, 

 especially by Tr'ichoderma lignorum against various species of Fusa- 

 rium and other fungi, as illustrated in Figures 16 and 17. 



Certain species of Trkhoderma and Gliocladium are able to inhibit 

 the growth of various plant pathogenic fungi, especially R. solani, as 

 well as of Blastomycoides dermatitidis , a causative agent of human skin 

 diseases. The active substance, gliotoxin, is liberated during the early 

 stages of growth. The mycelium of older cultures contains another sub- 

 stance that is soluble in acetone j this has only an inhibiting effect and is 

 not fungicidal as is gliotoxin. The fungicidal effect of gliotoxin upon 

 the germinating spores of Sclera tinia americana and hyphae of R. 

 solani was found to be greater than that of CUSO4 and less than that of 

 HgCU. 



Various other fungi are able to exert antagonistic effects against plant 

 pathogens. T. lignorum and A . niger restricted the growth of the fungi 

 Macrofhomina fhaseoli and R. solaniy which produce cotton root rot, 

 and reduced the activity of the filtrates of the pathogens causing wilting 

 of the plants. 



Satoh (826) has shown that Ofhiobolus m^iyabeanus produces both 

 growth-promoting and growth-retarding substances, the first of which 

 is heat stable and passes through a Chamberland filter j the second is 

 inactivated at 100° C. and does not pass through a filter. The formation 

 of two substances by Torula suganii, both of which were thermostable, 

 however, was also demonstrated (690). 



