Chemotropism in Rhizopus nigricans

Growth of Some Parasitic Fungi in Synthetic Culture Media

“…Our results in this connection are contrary to those of Graves (6), who states that a thermolabile" staling" substance is produced which-stops the growth of the fungus. If the acid is neutralized, Rhizopus nigricans will grow until Z~, the available carbon is completely used up.…”

“…If the acid is neutralized, Rhizopus nigricans will grow until Z~, the available carbon is completely used up. Our results in this connection are contrary to those of Graves (6), who states that a thermolabile" staling" substance is produced which-stops the growth of the fungus.…”

Chemotropism in Rhizopus Nigricans. Ii. The Action of Plant Juices

“…This growth behavior has been called the "staling reaction," as it is growth away from regions of stale medium. Clark's conclusion that molds have a negative tropic sensitivity to some product of their own metabolism has been adequately confirmed by later studies (Fulton, 1906;Graves, 1916;Stadler, 1952).…”

“…This was the view also of Fulton (1906), who looked for tropic action by a large number of substances on eight different molds ; he detected no positive tropism and concluded that orientation was based solely on the staling reaction. Graves (1916) recognized that the staling reaction caused the most marked orientation, but he reported that hyphae turned more pronouncedly toward a sugar-containing medium than toward plain water; thus, he concluded that sugar does exercise an attraction, but that it is normally masked by the stronger tropic action of the staling substance.…”

Studies on fusarium diseases of potatoes and truck crops in Minnesota

“…Lathrop (31) found aldehydes to be produced by F. rnbense E. F. Sm. Peltier ( 45) determined that a Botrytis produced a "harmful substance" that "may be some inorganic acid other than oxalic, or it may be a toxin of some kind, which, however, is not destroyed by heating to 100 degrees C." Graves (19) found that Rhizopus nigricans produced substances that exerted a negatively chemotropic effect upon the fungus greater than the positive chemotropic effect of certain food materials.…”