CHEMOTROPIC REACTIONS IN RHIZOPUS 

 NIGRICANS 



Arthur H. Graves 



Connecticut College for Women 



The question of the behavior of fungal hyphae in relation to 

 chemotropic stimuli has for some time been a rather weak ele- 

 ment in the groundwork of our knowledge of the physiology of the 

 fungi. Miyoshi,^ who was the first one to carry on any con- 

 siderable investigation of the subject, tested a large number of 

 chemical substances for their power of inducing chemotropic 

 reactions in fungal hyphae. As a result of this work he declared 

 that many of the substances exerted a positive stimulus, causmg 

 the hyphae to grow toward the diffusion centers, others a nega- 

 tive stimulus, so that the hyphae turned away, while still others 

 seemed to produce no effect. Without going into Miyoshi's 

 work more in detail here, the main thing for us to observe is his 

 conclusion that chemical substances do cause reactions, expressed 

 in more or less marked growth curvatures. 



The work was taken up again by Clark^ in 1902, and later In 

 1906 by Fulton.=^ The most significant thing about their investi- 

 gations was the fact that although using his same methods, they 

 were utterly unable to confirm Miyoshi's conclusions. Growth 

 curvatures of the hyphae were indeed observed, but apparently 

 not as a result of the stimulus of the substances tested. Among 

 his control experiments, Miyoshi had Injected leaves with pure 

 water, sowing spores on the leaf surface. No turning of the 

 hyphae through the stomata resulted in this case, although the 

 turning had been marked when the leaf was injected with, e. g., 

 cane sugar solutions. Clark Injected leaves with various con- 

 centrations of copper, cobalt salts, etc., and found that in this 



1 Miyoshi, M. Ueber Chemotropismus der Pilze. Bot. Zeit. 52: 1-28. 1894. 



2 Clark, J. F. On the toxic properties of some copper compounds with special 

 reference to Bordeaux mixture. Bot. Gaz. 33: 26-48. 1902. 



3 Fulton, H. R. Chemotropism of fungi. Bot. Gaz. 41: 81-108. 1906. 



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