1924] 
WOLPERT—FUNGI AND H-ION CONCENTRATION OF MEDIA 49 
employed. Table 1 indicates the method employed in making 
the solutions. 
Тһе nutrient solution, containing all of the nutrients except 
the phosphates, comprised 28 се. of the 35 cc. of each culture, 
or 80 per cent. Consequently all salts and sugar were weighed 
out on the basis of 1000 cc. of culture solution but made up to 
only 800 cc. with doubly distilled water. Twenty-eight ce. of 
this solution were added to each flask. Тһе addition of 7 се. of 
phosphate solutions to each culture resulted in bringing all 
nutrients to the desired concentrations. Тһе КН.РО, was 
added to the flasks before sterilization; the K,HPO, and H;PO, 
were autoclaved separately and added aseptically. Sterilization 
consisted in autoclaving for 15 minutes at 12-15 pounds pressure. 
This procedure eliminated, as far as possible, any alterations in 
the acidity of the solutions during autoclaving. The series Pg 
8.0 was obtained by adding, before sterilization, 0.5 gm. of СаСО; 
to flasks containing 7 cc. of K:HPO,. The reaction of this solu- 
tion varied from P, 7.8 to 8.2. All hydrogen-ion determinations 
were made according to the colorimetric method of Clark and 
Lubs (717) and Clark (720). 
TABLE I 
THE COMPOSITION OF THE MODIFIED RICHARDS' E SOLUTION ADJUSTED 
TO A RANGE ОЕ Рн FROM 3.0 TO 8.0 AT INTERVALS OF 0.5 
Initial No. ec. No. cc. No. се. No. cc. Тоба! 
Рн M/3 HPO, | M3 KH;PO,M/3 K:HPO, nutrient no. cc. 
solution 
3.0 i4 5.8 28 35 
3.5 0.5 6.5 28 35 
3.9 0.1 6.9 28 35 
4.4 . 7.0 28 35 
5.0 6.8 0.2 28 35 
5.5 6.3 0.7 28 35 
6.0 5.0 2.0 28 35 
6.5 3.5 3.5 28 35 
7.0 1.5 5.5 28 35 
7.6 7.0 28 35 
7.8-8.2 |0.5gm. СаСО; 7.0 28 35 
added 
The peptone-nutrient solution with sugar contained: bacto- 
peptone, 25 gms.; cane sugar, 30 gms.; MgSO,, 0.5 gm.; trace of 
FeSO., varying amounts of H;,PO, КН.РО,, and К.НРО; to 
