90 



c. Ammonium nitrate. — 5-25% -cultures were examined. The results 

 were as usual. 



Magnesium salts. 



Control-culture. — As above. 



a. Magnesium chloride. — 5-20 % -cultures were observed. Early 

 blackening &c. were similar to the cases of the other chlorides. Only it 

 had somewhat a weaker action upon my fungus, when compared with that 

 of potassium or sodium. 



b. Magnesium sulphate. — A 5% -culture formed white conidia on 

 the 4th day after inoculation , which coloured dirty brown on the 7th. 

 Coniclia-fruits 0.7 mm thick. In 10% conidia were white on the 4th, yellow 

 on the 6th and black on the 7th ; those of 20% white on the 5th, black on 

 the 7th. A 30 y fl -culture was characterized by a great diminution of the 

 size of reproductive organs : i.e. conidia-fruits 0.25 mm in diameter, conidia- 

 bearing hyphae 1.6 mm in length and 13/^ in thickness, with the cell- wall 

 of 2 fj. thick. This culture produced white conidia on the 6th clay, which 

 changed to black first on the 12th. The tendency of spore-blackening with 

 increase of concentration was an interesting phenomenon. 



Conclusions. 



1. As the concentration of the liquid-medium increases the conidia- 

 formation of Aspergillus niger is retarded. 



2. When the concentration of the medium ascends the conidia-fruits 

 are found to decrease in size. 



3. The stronger the concentration of the medium-solution becomes the 

 shorter are the conidia-bearing hyphae. 



4. With the concentration of the medium the blackening of conidia 

 is much promoted. 



5. In the solutions of strong concentration the conidia-formation is 

 entirely suppressed. 



ftendai. June 10, 1899. 



