802 
Journal of Agricultural Research 
Vol. XXXI, No.9 
in an Arnold sterilizer for approximately an hour. The liquid was 
then strained off and the original volume of liquid restored by addi¬ 
tion of distilled water. Agar 20 gms. and dextrose 20 gms. were then 
added and steamed a short time, and filtered while hot through 
absorbent cotton. Equal quantities of the medium were then placed 
in flasks and sterilized in an autoclave for 30 minutes at 10 pounds 
pressure. This medium was chosen as a standard and all stock 
cultures were grown on it. 
The nutrient broth was made by adding three grams of Liebig’s 
beef extract and 10 gms. of peptone to 1,000 c. c. of distilled water; 
the mixture was warmed and stirred until the peptone was dissolved, 
then filtered, placed in flasks, and sterilized in an autoclave for 30 
minutes at 10 pounds pressure. t 
Czapek’s full nutrient solution was made according to the following 
formula: 
Magnesium sulphate (MgS0 4 )_gm__ 0. 5 
Potassium dihydrogen phosphate (KH 2 BQ 4 ) _gm__ 1.0 
Potassium chloride (KC1)_gm__ .5 
Sodium nitrate (NaNCM_gm__ 2.0 
Ferrous sulphate (FeS0 4 )_gm__ .01 
Sucrose (Q 2 H 22 O 11 )_gm__ 30. 0 
Distilled water to make_c. c_> 1, 000 
Equal quantities were placed in flasks and sterilized for 30 minutes 
at 10 pounds pressure. The methods employed in adjusting the 
various media to different hydrogen-ion concentrations are described 
later under the heading of the influence of hydrogen-ion concentra¬ 
tion on growth of the fungus. 
String-bean agar, which proved to be most satisfactory for peri- 
thecial production, was prepared in the same manner as potato- 
dextrose agar, except that string beans were substituted for potatoes 
and the dextrose was omitted. 
A medium made from equal parts of oats and barley kernels proved 
to be favorable for increasing the fungus for purposes of inoculating 
soil. This medium enabled the fungus to make a luxuriant growth, 
and very little if any deleterious effect on the wheat plants resulted 
when the uninoculated medium was used in the soil in the controls. 
The grain mixture for this medium was first soaked over night in cold 
water and then boiled in an excess of water over a free flame for about 
an hour. Then 500 and 1,000 c. c. of the cooked kernels wereplaced 
in Erlenmeyer flasks of 1 to 2 liters capacity, respectively. Enough 
of the decoction water was added to each flask to keep the kernels 
moist, but not too wet, throughout the period the fungus was growing. 
The flasks were plugged with cotton and sterilized 45 minutes at 15 
pounds pressure. 
Following the inoculation, and after the fungus had thoroughly 
grown through the mass of kernels, the contents of the flasks were 
used to inoculate experimental soil. An equal quantity of inoculum 
was added to and throughly mixed with the upper soil in each con¬ 
tainer. Likewise in controls an equal quantity of the uninoculated 
medium was added. Immediately following this treatment wheat 
was sown in the inoculated and uninoculated soil. 
Other media, especially cooked wheat kernels, produced a somewhat 
better growth of mycelium, but it was found that these media were 
toxic to wheat plants. 
