782 



Journal of Agricultural Research 



Vol. XX, No. io 



Experiment 5. — This experiment was conducted in the same way as 

 experiments 3 and 4. The amyloclastic power of the enzym was de- 

 termined as in experiment 4. (Table XVII.) 



Table XVII. — Amount of reducing sugars and starch in the solution before and after 

 the growth of the fungus; also the hydrolysis of starch by enzym powder 



[Expressed in milligrams per io cc. of solution] 



An examination of the foregoing results shows a clear case of the 

 regulatory influence of the culture medium on the quantitative secretion 

 of amylase. In every case where starch (series a) alone was used as the 

 source of carbon the enzym powder hydrolyzed several times as much 

 starch in a corresponding length of time as when glucose alone (series b) 

 or in combination with starch (series c) was used. On the other hand, 

 the enzym powder from sweet potato bouillon (series d), which always 

 contained reducing sugars and starch and probably other carbohydrates, 

 hydrolyzed considerably more starch than the powder from the a series. 

 This exception is hard to explain, since it was obviously impossible to 

 determine the exact composition of sweet potato bouillon. That it 

 was a better medium for the growth of the fungus was quite evident. 

 The quantity of felt was always greater than in any of the other series. 

 The growth in the a series was likewise better than in either the b or c 

 series, starch alone appearing to be a better source of carbon than glucose 

 alone or in combination with starch. 



These results seem to indicate that within the limits of these experi- 

 ments the solution which is best for the growth of the fungus is likewise 

 best for the secretion of amylase, regardless of the source of carbohy- 

 drates. It is probable that it is not so much the source of the carbohy- 

 drate which influences directly the quantitative production of the enzym 

 as the influence it has upon the growth of the fungus on which the secre- 

 tion of the enzym depends. 



INFLUENCE OF THE AGE OF THE MYCELIUM WHEN REMOVED FROM THE 

 CULTURE ON THE PRODUCTION OF AMYLASE 



It was shown by Dox, Young, and others that the greatest amount of 

 enzym is contained in the mycelium at about the beginning of the fruit- 



