230 



culture solution containing 1% glucose were put into Erlenmeyer 

 flasks of two différent sizes, six of each. The surface In the small 

 flasks was 26 squ.c.M. in the big flasks 82 squ.c.M. They were 

 inoculated. on the same day; observations were made on the 8* 

 14 and 2P days. The results can be seen from the followlng 

 table t 



From this table we see, that during the first week the sécrétion 

 of enzyme, the dry weight of the mycélium, as well the degree of 

 acidity are less in the cultures with the smaller exposed surface. 

 After the first week or so however, thèse things are equalised. 



The investigations made during the last twelve years on the in- 

 fluence of the hydrogen ion concentration on the action of enzymes, 

 forced me to find, how the diastase o{ Aspergillus niger reacts to 

 the acidity of the culture médium. I was sure from the beginning 

 that it could not be without any influence at ail, because Asper- 

 gillus niger produces very much acid and the amylase it secrètes 

 must therefore work at a high hydrogen ion concentration. 



This investigation was made in the way, first described by 

 Sôrensen. It is based on the use of standard solutions, the hydrogen 

 ion concentration of which is known. Thèse standard solutions 

 and the liquids, the Ph of which we wish to détermine are co- 

 loured by indicators, so that we can détermine the turning point 

 exactly by comparing the colours. The standard solutions I used. 



