(Vor. 11 
48 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
been adequately described in the papers referred to and in later 
papers from this laboratory, so they require no discussion at 
this point. The spore method was used when it was impossible 
to secure sterile tissue, as from particularly thin sporophores. 
After the mycelium had made considerable growth upon potato 
agar, the cultures were transferred to large bottles of sterile 
bean stems and pods, to sterile decayed wood, and to sterile 
decayed wood mixed with decayed leaves. Growth was more 
rapid in the bean stem and pod cultures, but in all cases it was 
abundant enough to constitute satisfactory stock cultures. 
Inoculum was prepared according to the method of Zeller, 
Schmitz, and Duggar (719) by growing bits of mycelium from 
these stock cultures upon plates of sterile agar made according 
to the following formula: 1000 сс. potato water from 240 gms. 
of potatoes boiled for 1 hour, 20 gms. cane sugar, 10 gms. KNO;, 
5 gms. КН.РО,, and 20 gms.agar. After a growth period of 10 
days to 2 weeks, these plates were cut into pieces 8-10 mm. 
square. Each culture flask received 1 of these squares of inoculum. 
` Culture solutions.—The culture media сап be divided into 
two classes, based on the absence or presence of celluloses. The | 25 
first class consists of 3 types, as described later, namely: (1) 
8 modifieation of Richards' E solution, (2) a peptone-nutrient 
solution with sugar, and (3) a peptone-nutrient solution without 
sugar. 
The modified Richards’ E solution contained: MgSO, 0.5 
gm.; KNO, 5 gms.; NH,NO,, 10 gms.; trace FeSO,; varying 
amounts of H;PO,, KH;PO,, and K;HPO, to give a total of 10.4 
gms. of phosphate; and doubly distilled water, 1000 cc. The3 _ | 
forms of the phosphate were used in varying proportions to obtain 
a range of reaction from P, 2.5 to 8.0 at intervals of 0.5. Тһе 
large percentage of phosphates and the reduced amount of sugar 
produeed a heavily buffered solution which held, as nearly аз 
possible, the initial Ри throughout the entire incubation period. 
The amount of MgSO, was reduced because in the presence of | 
phosphates it produces a precipitate in an alkaline solution. | 
Although all precautions were taken in making the media, 
slight differences in Ри were evident in each series, requiring | 
some slight variation in the proportion of the phosphate buffers 
