TITRATION CURVES OF CERTAIN LIQUID CULTURE 
EDIA 
JOANNE L. KARRER 
Research. Assistant to the Missouri Botanica! Garden 
AND ROBERT W. WEBB 
Rufus J. Lackland Fellow in the Henry Shaw School of Botany of 
Washington University 
A study of the growth of various fungi and of the germina- 
tion of various fungous spores with reference to H-ion concen- 
tration has involved a determination of the titration curves of 
several culture media. It is the purpose of this paper to present 
briefly the data obtained with these nutrient solutions, which 
have been the basis of subsequent work in this laboratory. 
The formulae for the media employed are as follows: 
Beet decoction.—Prepared according to the method outlined 
by Duggar, Severy, and Schmitz (17). This consists essen- 
tially of 370.4 gms. of sugar beets per liter of distilled water, 
autoclaved at 15 pounds for one hour, and then filtered. 
Czapek's solution—MgSO.+7 H:O, .5 gm.; KH.PO, 1.0 gm.; 
KCl, .5 gm.; NaNO,, 2.0 gms.; FeSO, .01 gm.; cane sugar, 
30.0 gms.; distilled H.O, 1000 cc. (Zeller, Schmitz, and Duggar, 
19). 
Peptone solution.—Twenty gms. bacto-peptone in 1000 cc. 
H;O. 
Pfeffer's solution. —KH;PO,, 5.0 gms.; MgSO.+7 H.O, 2.5 
gms.; NH,NO,, 10.0 gms.; FeSO,, trace; cane sugar, 50.0 gms.; 
distilled H.O, 1000 cc. (Pfeffer, '95). 
Richards’ solution. —KH.;PO,, .5 gm.; KNO,, 4.0 gms.; MgSO, 
+7 H-O, .5 gm.; NH.NO,, 10.0 gms.; FeSO,, trace; cane sugar, 
30.0 gms.; distilled H.O, 1000 cc. (Richards, '97). This formula 
differs from that of the original by a reduction in the amount 
of MgSO.. The amount of precipitate produced in the more 
alkaline solutions was found to depend largely upon the amount 
of magnesium present, and, since it is important to keep the 
amounts of the constituents in the solutions as nearly equal as 
possible while varying the H-ion concentration, it seemed desir- 
able to reduce the amount of MgSO, to .5 gm. per liter. Such 
Ann. Mo. Bor. Ganp., Vor. 7, 1920 (299) 
