261 



there appeared compact, rolled up and detached bits of mycélium, 

 which floated on the surface of the liquld. They were light grey 

 because of the conidia, which were closely attached to them. 



As can be seen from both tables, there is no production of dias- 

 tase in either of the séries worth while mentioning. But we may 

 not conclude from this, that A spergillus ni ger produces no diastase 

 on glycérine. We ought to find out first, if we can obtain the same 

 results with lower concentrations of glycérine, as we got with 1% 

 cane sugar. At présent I can only state, that in cultures an 5% gly- 

 cérine, the factors which possibly inhibit the production of diastase, 

 hâve not yet disappeared after 52 days. 



Two parallel séries were also grown on 5% lactose. On this 

 culture solution there was almost no development. There seems 

 to be no lactase in Aspergillus niger and consequently it can not 

 be produced, even if it is necessary. The rotation of the culture 

 solution was 2"28'3" on the first day and 2'^24'36" on the \9^^ 

 day. There were very small bits of pellicle formed, which were 

 so scanty, that they only became visible, when coloured by the 

 development of conidia. As thèse results are of no importance, I 

 hâve not tabulated them; it is almost superfluous to mention, that 

 no amylase was produced. 



V. SUMMARY. 



Before we experiment with the enzymes of fungi, it is impera- 

 tive that we should know, what hydrogen ion concentration is 

 wanted for the optimal reaction of thèse enzymes. Aspergillus niger 

 produces the necessary degree of acidity in its own culture solu- 

 tion. This however is not the case with ail fungi. 



It is of the utmost importance to know, what nutrient base is 

 used in the cultures, from which we obtain the conidia for our 

 experiments. It is always best to take thèse conidia from cultures 

 on solutions of the same chemical composition as those, on which 

 we intend to grow them. 



Aspergillus niger produces large quantities of diastase from the 

 beginning of its development until a maximum is reached. Then 



