1922] KNUDSON—ORCHID SEEDS I5 
In an experiment with seeds of Epidendron growing on solution 
B plus o.80 per cent glucose, one of the cultures became con- 
taminated with a species of Actinomyces. The result was that when 
the embryos in the contaminated culture were dark green, with 
one and two leaves, the embryos in corresponding uncontaminated 
cultures were still white or yellowish and only one or two of them 
showing the leaf point. In the contaminated culture the embryo 
Ge? 
2.—Culture no. 1, solution B+2 per cent glucose contaminated by Actino- 
myces ne (corresponding check like no 3); culture no. 2, Pfeffer’s +2 per cent sucrose 
inoculated with Bacillus radicicola; culture no. 3, same but not inoculated; culture 
no. 4, solution B+2 per cent glucose; culture no. 5, solution B+ 2 per cent glucose 
inoculated with B. radicicola; x 4. 
had an average width of 975, while in the uncontaminated cultures 
the average width of the embryos was 6oou. 
In view of these observations, and since BoTroMLEy reported 
a beneficial effect on the growth of Lemna by the addition to the 
nutrient solution of an aqueous extract of Azotobacter or of Bacillus 
radicicola, an experiment was made to determine the influence of 
the latter organism on germination. Ten tubes were prepared 
with Pfeffer’s solution plus 2 per cent sucrose; five were inoculated 
with B. radicicola from alfalfa, and five were left uninoculated. 
Seeds of Epidendron were sown on December 18, 1920. On March 
5, 1921, 80 per cent of all the seeds in the inoculated tubes had 
