Feb. is, 1921 



Amylase of Rhizopus tritici 



763 



minutes. When air-dry the mycelium was put into small flasks and 

 held at a temperature of 9 C. until required for use. Experiments to 

 be discussed later will show that the mycelium can be held at 9 or even 

 higher for several months without any appreciable loss in its ability to 

 hydrolyze starch. 



The hydrolysis by the mycelium or extract was carried out in 150-cc. 

 pyrex flasks. A weighed portion of the mycelium was ground in fine 

 quartz sand and transferred to the flasks, to which was added a measured 

 quantity of the starch paste solution made in distilled water. While 

 the percentage of starch is not material, a 0.5 per cent solution was used 

 for most of the work. After the addition of 2 cc. of toluol to each flask 

 as an antiseptic it was plugged by a cork with a small groove at the side 

 to allow for the escape of the expanded air when steamed at the close of 

 the experiment. Hydrolysis was carried out at different temperatures, 

 the results of which are shown elsewhere. 



C. P. chemicals were used in the preparation of the culture media. 

 The Irish potato starch was obtained from Ehner and Amend. The 

 sweet potato starch was prepared by the writer. Preliminary experi- 

 ments showed that neither contained any reducing sugars. The sand 

 used for grinding the mycelium was purified by washing in distilled 

 water and then burning for an hour or more in a crucible. The water 

 in which sand so prepared was suspended did not reduce copper. 



At the close of the digestion period the enzym was inactivated by 

 steaming the flasks in an Arnold steam sterilizer for about 15 minutes. 

 To avoid evaporation during the process of heating, oiled paper was 

 fastened with a rubber band over the cork and around the neck of the 

 flask. Before this method was finally adopted tests were made to deter- 

 mine the temperature reached in a given volume of solution in a given 

 length of time. Table I shows the results of these tests, made with tap 

 water in Erlenmeyer flasks, with an initial temperature of 14 to 15 C. 

 There was a small slit at the side of the cork to allow for expansion, and 

 a thermometer was run through it, with the bulb submerged in the water. 



Table I. — Temperature reached by a certain volume of water when heated a given length 

 of time in an Arnold sterilizer {average of several tests) 



The loss of water by the use of the method described above was less 

 than 0.1 gm. in a flask of 150-cc. capacity containing 100 cc. of solution. 

 25120°— 21 3 



