INULASE FORMATION IN ASPERGILLUS 77 



of starch alone in the culture medium stimulates the fungus to 

 form large amounts of amylase. Small amounts of cane sugar 

 or glucose (1.5 to 2%) largely inhibit the formation of amylase. 

 Lactose in 10% solution retards the formation of amjdase, but 

 a 3% solution has no effect. The effect of maltose is somewhat 

 similar. Katz shows that the action of amylase itself is not 

 affected by the presence of sugar in the concentrations used. 



The inhibitory effect of sugars on amylase formation in As- 

 pergillus niger as described by Katz (1898) is nmch less marked 

 than in Pe9icilliu7n glaucum and even as large an amount as 30% 

 does not entirely inhibit its formation. The inhibitory eft'ect of 

 maltose, erythro-dextrin, glycerin, tartaric acid and quinic acid 

 decreases from first to last in the order named. He finds that 

 Aspergillus niqer on culture media with starch only grows very 

 feebly and forms only a small amount of diastase, but that the 

 addition of 1.5% of sucrose stimulates both the growth of the 

 fungus and the amount of enzyme formed. Katz believes that 

 the inhibitory effect of these substances on amylase formation is 

 not in proportion to their mass but that the effect is purel}'' 

 stimulatory. 



In the case of Aspergillus glaucus and Penicillium glaucum Du- 

 claux (1899) concludes that there is a certain qualitative enzyme 

 production, and that enzyme formation in Penicillium glaucum 

 depends upon nutrition. He, however, investigated only those 

 enzymes which were secreted into the culture medium, taking no 

 account of the enzyme content of the fungi themselves, which 

 cannot be considered as a sufficient criterion. 



Herissey (1899) in a thesis entitled "Recherches sur I'Emul- 

 sine," among other problems has studied the conditions, leading 

 to the appearance of emulsion in Aspergillus iiiger, and finds 

 that cultures growm on Raulin's solution for twenty-three to 

 twenty-five hours give no indication of the presence of emulsin, 

 but, w'hen left for forty-eight hours, a vigorous emulsin is ob- 

 tained. If Aspergillus is grown on Raulin's solution containing 

 three to four times as much ammonium nitrate as usual, and the 

 amount of ammonium nitrate used is replaced at the end of e\'ery 

 twenty-four hours such cultures grow for a month without sporu- 



