CHEMICAL STIMULATION OF GROWTH OF ASPERGILLUS NIGER 33 1 
Composition of Ash 
Top Yeast Bottom Yeast 
H3PO4 41.8% 39.5% 
K 39.8 28.3 
Na — — 
CaHP04 2.3 9.7 
MgHP04 16.8 22.6 
Si02 tr. — 
substituted various compounds, singly and combined, for the yeast ash 
in the Pasteur nutrient solution and determined the extent of growth as 
represented by the dry weight of the tissue formed. The "most useful" 
substances in the order of their importance were, according to Raulin: 
ammonium phosphate, potassium carbonate, magnesium carbonate, am- 
monium sulphate, and manganese carbonate. 
In 1869 a continuation of these studies was published by Raulin (55), 
and almost simultaneously appeared an important contribution by A. 
Mayer (38). 
Raulin had continued his studies on Aspergillus niger, arriving at a 
nutrient solution ''essai type" which contained, as he held, all the elements 
''essential" for the growth of this organism in the proper proportions. The 
omission of any component of his "essai type" solution resulted, he stated, 
in a large decrease in growth. I repeat the formula as a matter of historical 
interest: water 1,500 g., cane sugar 70.00 g., tartaric acid 4.00 g., ammonium 
nitrate 4.00 g., ammonium phosphate 0.60 g., potassium carbonate 0.60 g., 
magnesium carbonate 0.40 g., ammonium sulphate 0.25 g., zinc sulphate 
0.07 g., iron sulphate 0.07 g., potassium silicate 0.07 g. 
As a result of his studies on the "normal" development and respiration 
of a yeast, Mayer (38) had arrived, however, at a much simpler nntrient 
solution, containing, if we exclude from consideration the water and cane 
sugar, but four compounds as compared to the nine entering into the com- 
position of the nutrient solution as worked out by Raulin. The elements 
Mayer considered "essential" are present in this solution in the proportions 
most favorable for "normal" development and respiration. Moreover, 
these proportions, Mayer points out, closely approximate those found in 
the yeast ash. The formula of the Mayer solution is: water 1000.0 g., 
cane sugar 150.0 g., ammonium, nitrate 10. o g., monopotassium phosphate 
5.0 g., magnesium sulphate 2.5 g., calcium phosphate (CaHP04) 0.5 g. 
A comparison of these two formulae with respect to the elements 
present shows a substantial agreement. Both solutions contain hydrogen, 
oxygen, carbon, nitrogen, phosphorus, sulphur, potassium, and magnesium. 
Raulin included in addition zinc, iron and silicon; Mayer, calcium only. 
With respect to the necessity of silicon the evidence is as yet indecisive. 
Calcium has, however, been shown by Benecke (3) not to be an "essential" 
element in the nutrition of fungi. 
