774 Journal of Agricultural Research vol. xx.No. 10 



although in such solutions no starch was present, if judged by the iodin 

 test. This difference might be explained by the presence of dextrins as 

 intermediate products. Brown (j) claims that in the action of diastase 

 on starch the reaction ends when the composition of the product is 80.8 

 per cent maltose and 19.2 per cent dextrin. Maquenne and Roux (21), 

 however, suggest that the equilibrium of 80.8 per cent maltose and 19.2 

 per cent dextrin referred to above is due to insufficient activity of the 

 enzym and that if malt diastase is activated by acid in small amount 

 the whole of the starch is found to be converted into sugar, so no dextrins 

 remain. Bayliss (2) found that the amount of maltose produced in the 

 first stage was greater than the equilibrium position of Brown and 

 Heron because it was allowed to proceed for a longer time. 



Although the writer did not use a temperature above 40 C, this 

 temperature might have had some bearing on the proportion of sugar to 

 dextrins, in accordance with the interesting results of Brown and 

 Heron (5). 



These investigators found that the dextrinase is more injured by a 

 temperature of 68° C. than the amylase. According to this theory they 

 explain the fact that when starch paste is acted on by diastase which 

 has been exposed to a temperature of 68° there is less maltose and more 

 dextrin formed than when the enzym has not been so heated. This 

 raises the question as to just where the influence of temperature makes 

 itself felt. Furthermore, facts which might bear upon the question 

 were brought out by Tammann (2j), who reports that an increase of 

 hydrolysis was obtained in a stationary system by altering any of the 

 other conditions of the equilibrium, such as the addition of more amyg- 

 dalin, renewal of the products of the reaction, raising the temperature, 

 or increasing the dilution. In Tammann's work the retardation would 

 virtually be due to the accumulation of the products of the reaction. 



GROWTH AND HYDROLYSIS IN A SOLUTION OF STARCH PASTE 



The remarkable power of Rhizopus tritici to grow on almost any kind 

 of medium is evident when we consider that it can be isolated from a 

 great variety of decayed substances. Its ability to hydrolyze starch in 

 a solution poor in nutrient material was tested several times by inoculat- 

 ing a starch paste solution made with distilled water. While such a 

 solution would contain nutrient substances in addition to the carbo- 

 hydrates introduced in the form of starch, a considerable growth would 

 hardly be expected, but, nevertheless, a fair growth was made and 

 hydrolysis of the starch went on. 



The experiments were made in Hrlenmeyer flasks containing 500 

 cc. of a 0.5 per cent starch paste solution. Some of the inocula- 

 tions were made with bits of mycelium and spores and some with spores 

 alone. Growth was slow at the outset, the colonies being submerged 



