77 



My cultures of moulds verified the results of Kichards. Corrosive 

 sublimate and copper sulphate were proved to be no exception in this case. 

 With almost all the salts experimented, it was found that they retarded 

 the formation of spores. This was especially the case with zinc sulphate 

 and sodium fluoride. 



As is well known, Aspergillus niger produces a considerable quantity 

 of oxalic acid during its development. I have measured the quantity of 

 the acid in the respective cultures of Aspergillus, and found the quantity 

 of the acid to be always considerably smaller in those cultures in which 

 the substances in question were added (with the only exception of nickel 

 sulphate). 



This fact may be accounted for in more than one way, inasmuch as 

 the detected quantity of the acid do not represent the whole quantity of 

 the excreted acid, the decomposition being possible to go on hand in hand 

 with the excretion. Firstly, it might be interpreted thus: although oxnlie 

 acid is excreted normally as metabolic product of Aspergillus, yet it is to 

 be looked upon as the product of the incomplete physiological combustion; 

 so it might happen that when on the enhancement of the metabolic process, 

 carbonic acid gas, being the product of complete combustion, would be 

 produced instead of oxalic acid, and consequently the production of the 

 latter would be diminished. 



The second possibility is that the excreted acid is again worked upon 

 through the activities of the fungus. 



Thirdly and lastly, it might bring the same result, if the carbohydrates 

 taken as food which might have normally been excreted partly as oxalic 

 acids, by metabolism in the presence of substances in question, instead of 

 being given off as such, but would have been used up directly to be the 

 integral part of the mould. 



To see in what relation the acceleration of dynamic metabolism stands 

 to that of constructive one, I have calculated the ratio of the consumed 

 ineterial to the cropped mass, known under the name of the economic 

 coefficient. The coefficient for sugar was calculated with zinc sulphate cul- 

 tures. i n which the acceleration of growth was by far the most pronounced. 



The results of one of such experiments are given below : 



Content of ZnS0 4 " 0-00379$ 0*0074# 0-0148^ 0'0297% 



Dry wt, of mould in mg. 262 860 875 785 773 



Sugar consumed in mg. 1594 2429 2429 2380 2340 



Economic coeft. 6-0 2-8 2-8 3-0 3*2 



