778 Journal of Agricultural Research vol. xx, No. 10 



growth occurs at 29 . At first thought one might suspect that at the 

 higher temperature the enzym diffuses out into the solution more readily 

 than at the two lower temperatures, and, indeed, one can not say such is 

 not the case. If the hydrolytic capacity of the enzym corresponded to 

 the growth of the fungus in the nutrient solution, as it does not, such a 

 theory might receive strong support. The poorest growth is at the 

 lowest temperature. At 9 the mycelium was mostly submerged, and 

 no fruiting had taken place. On the other hand, at 29 and 40 a thick 

 felt had formed, with some fruiting, though less at 40 than at 29 . 



QUANTITATIVE REGULATION OF AMYLASE 



The results of many investigations have shown a quantitative regula- 

 tion of certain enzyms of various fungi. Brunton and MacFayden (7) 

 found that a bacterium produced diastase when cultivated on starch 

 paste but not when grown on meat broth. In the latter case a pep- 

 tonizing enzym was produced. Pfeffer (22) found that in several mold 

 fungi the secretion of diastase depended upon similar conditions, and 

 Brown and Morris (6) claim a similar regulatory action with barley, in 

 that when readily assimilable substances were supplied the secretion of 

 diastase did not take place, but when no such substances were available 

 diastase was formed at once. It was likewise found by Wortmann (27) 

 that certain molds had the power of excreting a starch-dissolving enzym 

 when starch grains were the only available food and that no secretion 

 took place if sugar or tartaric acid was offered to the organism along 

 with the starch. More recent workers have arrived at similar results 

 with different fungi. Went (25) showed that Monilia sitophila secreted a 

 number of enzyms, some of which were produced only when the particu- 

 lar substance on which they act was present in the culture solution. 

 Others were produced when substances chemically allied to the products 

 of hydrolysis were present. In general, however, he concluded that the 

 secretion of enzyms was not a hunger phenomenon, since those fungi 

 which were best nourished produced the most enzym. Dox (9), on the 

 other hand, demonstrated that for Penicillium camemberti, at least, the 

 enzyms were secreted regardless of the chemical nature of the substrate. 

 He found that by cultivating the fungus on a particular substratum the 

 quantity of the corresponding enzym may be increased, but that no 

 enzym not normally produced by the organism could be developed by 

 any special method of nutrition. Katz (16) in 1898 published the re- 

 sults of the regulating action of certain chemical substances in the 

 solution of the regulatory secretion of amylase by P. glaucum, Aspergillus 

 niger, and Bacillus megatherium and found that while the amylase secre- 

 tion was not prohibited by the presence of substances chemically allied 

 to starch, their effect was greatly to inhibit it. He found that the differ- 

 ent fungi did not respond exactly in the same way and cites as proof the 

 results with A. niger and P. glaucum. The presence of sugars ra the 



