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MISSOURI BOTANICAL GARDEN. 



periments were made with sand, garden soil and leaf mold. 

 From these experiments it was found that leaf mold was the 

 best medium, of those experimented with, for the germina- 

 tion of the spores. In preparing the pots for sowing the spores, 

 they were filled to a depth of about an inch and a half with 

 either coarse cinders or broken pieces of pots. Upon this a 

 layer of garden soil was placed which extended to within 

 about an inch of the top of the pot. This soil layer was then 

 covered with a layer of sifted leaf mold to within about a 

 quarter of an inch of the top. The pots were then thoroughly 

 sterilized in a Koch steam sterilizer. Just before sowing the 

 spores the pots were completely saturated with sterilized 

 water. After the spores had been sown, glass plates were 

 placed over the pots and they were imbedded in the germina- 

 tion boxes. The pots were not watered directly, but the 

 soil surrounding them was kept well moistened. 



Two special germinating boxes were prepared; one for 

 germination in strong light, and the other for germination in 

 absence of light. The box for strong light had a glass front 

 and cover, and was painted white on the inside. The box 

 for germination in darkness was constructed so as to exclude 

 light and at the same time to allow some access of air. This 

 was accomplished by means of a closely fitting sliding cover 

 which overhung the lower part of the box one end of 

 which was perforated. A thermometer was placed in the 

 cover of this box. Petri dishes were also used for germinat- 

 ing spores. Two or three thicknesses of filter paper were 

 placed in each of them, and they were then filled about one- 

 third full of 0.5% Knop's solution, and sterilized before the 

 spores were sowed. These cultures, as well as some upon leaf 

 mold, were kept in an incubator at a temperature of from 

 30° to 33° C. As a means of exposing the spores to one-sided 

 illumination during germination, black paper was placed upon 

 Petri dishes, leaving an opening on one side for the entrance 

 of light. 



The intensity of the light was determined by a light meter 

 used for determining the time of exposure in photographic 

 work. The time required for bright sunlight to change the 

 sensitive paper to the standard tone was taken as the unit. 



