6o MYCOLOGY 



means. Details of the occurrence of the above enzymes will be found 

 in the books noted in the footnote below.' 



CHEMOTAXIS 



The attraction or repulsion of motile microorganisms by chemical 

 stimulants known as chemotaxis is found in the activity of the zoospores 

 of the OOMYCETALES and in the growth of the hyphae of fungi in gen- 

 eral toward or away from the stimulus. To these phenomena the names 

 of positive and negative chemotropism have been given. The thorough 

 investigations of M. Miyoshi with Aspergillus niger, Mucor mucedo, 

 Penicillium glaucum, Phycomyces nitens, Rhizopus nigricans have shown 

 that the following substances act as powerful stimulants: ammonium 

 phosphate, asparagin, dextrin, saccharose and glucose. The threshold 

 value (marginal limit) or minimum quantity capable of producing a 

 chemotactic effect was ascertained by Miyoshi as o.oi per cent, in 

 the case of glucose acting on Mucor mucedo. On gradually increasing 

 the dose, a second limit is reached where repulsion occurs. The 

 entrance of fungi into leaves and the growth of hyphae along certain 

 lines inside of the host tissue and the formation of haustoria are per- 

 haps all indications of chemotropic response. 



iRayliss, W. M.: The Nature of Enzyme Action (Monograph on Biochem- 

 istry). Longmans, Green & Co., 1914. 



Green, J. Reynolds: The Soluble Ferments and Fermentation. Cambridge 

 at the University Press, 1899. 



Haas, Paul and Hill, T. G. : An Introduction to the Chemistry of Plant Prod- 

 ucts. London, Longmans, Green & Co., 1913. 



Harden, Arthur: Alcoholic Fermentation (Monograph on Biochemistry). 

 London, Longmans, Green & Co., 1914. 



Lafar, Franz, transl. by Salter, Charles, T. C: Technical Mycology, ii, 

 Pt. I : 61-65. 



Marshall, Charles E. and others: Microbiology. Philadelphia, P. Blakiston's 

 Son & Co., 1911 



Oppenheimer, Carl: Die Fermente und ihre Wirkungen. Leipzig, 1903. 



Vernon, H. M. Intracellular Enzymes. London, John Murray, 1908. 



