766 Journal of Agricultural Research voi.xx.No. 10 



While an examination of Table II shows that both raw Irish and sweet 

 potato starch are hydrolyzed, no large amount of invert sugars are pro- 

 duced after hydrolyzation is carried on for 17.5 to 18 hours. Grinding 

 the starch in fine quartz sand does not seem to influence the amount of 

 hydrolysis appreciably. 



That starch paste is more readily hydrolyzed than raw starch is evident 

 from the results of the following experiments. Two sets of flasks were pre- 

 pared to contain 0.2 gm. of powdered mycelium. To one set were added 

 100 cc. of sterile distilled water and 0.5 gm. of raw sweet potato starch, 

 and to the other 100 cc. of water containing 0.5 gm. of starch paste. A 

 third set contained 100 cc. of water and 0.2 gm. of mycelium but no starch. 

 Toluol was added as an antiseptic. Hydrolysis was carried on for 18 

 hours at 40 C. In the set with water and mycelium 1.98 mgm. of reduc- 

 ing sugar, representing autolysis of the fungus, were found per 10 cc. of 

 solution. This amount of reducing sugar was deducted from the results 

 obtained from the other two sets. Reducing sugars equivalent to an 

 average of 1.20 mgm. per 10 cc. of solution were obtained from the raw 

 starch, while 27.95 mgm. were obtained per 10 cc. from the starch paste 

 solution, or an amount more than 23 times as large. 



INFLUENCE OF AGE OF MYCELIUM ON POWER OF HYDROLYSIS 



To carry out any considerable number of comparative experiments at 

 different times the mycelium must be produced in quantity and kept for 

 some time. Before such material could be used for comparative studies 

 it was necessary to determine whether the mycelium lost its power of 

 digestion with age, and if so to what extent. 



The mycelium was grown in large flasks on sweet potato bouillon. 

 At the end of 8 days' growth it was removed and prepared according to 

 the method already described. Hydrolysis was carried out at different 

 times at a temperature of 27. 5 C. for 19 hours by the use of 0.25 gm. of 

 powdered mycelium. A starch paste solution was prepared which con- 

 tained 53.4 mgm. of starch per 10 cc. of solution. This sterilized starch 

 solution was tightly stoppered to prevent evaporation and contamina- 

 tion and was stored at a temperature of 9 . Two days after the mycelium 

 was collected the first experiment was conducted. Fifty cc. of the starch 

 paste and 0.25 gm. of the mycelium finely ground in sand were used in 

 150-cc. pyrex flasks, with 2 cc. toluol added as an antiseptic. Two flasks 

 with mycelium and starch paste and one control flask containing myce- 

 lium and 50 cc. of water were used in each test. The amount of autolysis 

 was deducted from the average of two closely agreeing samples. The 

 results appear in Table III. 



There was a slight decrease in the amount of reducing sugars in the tests 

 of the last three months. From the results it seems safe to conclude that 

 the mycelium may be kept for several months without any appreciable 



