224 



was adopted: I made a solution of potato starch which had been 

 prepared by Lintner's method; 1 Gr. of this starch was dlssolved 

 in 1250 ce. water (therefore a solution of 0.08*^o)- The water was 

 constantly stlrred to pievent boiling. A quantity of this solution, 

 as as rule 25 ce, was mixed with an equal volume of the liquid, 

 which had to he examined; the time at which this took place was 

 noted. From time to time a small portion of this mixture was 

 taken away, after thoroughly shakin^ the liquid. This portion was 

 tested for the présence of starch and erythrodextrine by the addi- 

 tion of a little dilute solution of J in JK\ When the liquid re- 

 mained yellow without the slightest touch of red, I took it for 

 granted that ail the starch was hydrolysed. Of course it is rather 

 difficult to find the exact time, taken for complète hydrolysis, but 

 it can best be determined by taking the mean cf the time taken by 

 the last test showing a faint redish-yellow tint and the first test 

 that remains yellow. I was always very careful to hâve thèse last 

 two observations as close to each other as possible. In most cases 

 the time, taken for hydrolysis could be expressed in minutes, some 

 of the shortest only took seconds to be complète. 



Went divided the mixture of mycélium extract or culiurt so- 

 lution and starch equally among?t a large number cf test tubes. It 

 bas however been observed that the distribution cf the enzyme in 

 the liquid is not always quite homogeneous. In this way it has 

 happened that hydrolysis proceeded faster in onc test tube than 

 in another. For this reason it is m.y imperative to shake the liquid 

 thoroughly before taking a portion of it for testing. Besides pipet- 

 ting an equal amount of the solution into a large number of tubes 

 only lengthens the expenment unnessecarily. 



Making use of the time taken for hydrolysis, I estimated the con- 

 centration of diastase in the same way as Went. I took the amount 

 of diastase to be = 100 if the time, taken for hydrolysis under 

 the above conditions was 150 min. If for instance in a given 



^ Although there were sometirnes small différences in the concentration of the 

 iodine. I never reniarked, any influence of it. 



