Mar. 12, i£i7 
Fusarium-Blight of the Soybean 
429 
In order to obtain sterile seedlings for this purpose the seeds 
were first washed for 5 minutes in tepid water and were then placed 
in concentrated sulphuric acid for 20 minutes. Formalin, mercuric 
chlorid, both in aqueous and alcoholic solution, and other disinfect¬ 
ants were employed with much less success. After washing off the 
acid in three or four changes of sterile water, the seed were trans¬ 
ferred into sterilized moist chambers in the bottoms of which several 
layers of moist filter paper had been placed. Germinated seeds on 
which there was no evidence of contamination after a day or two were 
transferred to sterile test tubes 1 the bottom of each of which contained 
a wad of moistened filter paper. 2 If, during germination or transfer, 
contamination occurs, it generally becomes evident on the seedlings or 
white paper, especially if the seedlings are set aside until they have 
grown to a height of 3 or 4 inches. 3 
methods oe study and presentation 
All transfers of different strains in a set for comparison were made to 
a certain medium on the same day and to additional media on later 
days until the set was growing on a sufficient number of media to provide 
the necessary cultural characters. When species were compared, they 
were always of the same age and were grown on the same medium. 
As many comparisons could be made on the same day as t there were 
species and kinds of media in the set. If sufficient data had not been 
obtained, if certain cultures were abnormal, or if other species or media 
were to be used, new sets were prepared of all of the species using the 
desired media and comparisons were again made throughout the series. 
Cultural differences also arise as a result of the employment of spores 
or a bit of mycelium in inoculation. In t&e former case the young cultures 
quickly produce spores with a scant mycelial growth, while in the latter 
the mycelial growth is abundant and there is a paucity of spores. For 
this reason spores from sporodochia, when present, were used, and in all 
cases, in so far as was possible, the same kind of inoculum was trans¬ 
ferred for all cultures of a set. When the production of spores becomes, 
subnormal, as it often does in cultures, considerable time and patience 
may be required to bring the strain back to a “ Normkultur.” This was 
accomplished by transferring a small portion of mycelium to a variety 
of media until a medium was found on which spores were again obtained. 
1 For making this last transfer, dip the ends of long tweezers into 95 per cent alcohol and ignite in the 
flame. This sterilizes instruments, bums off the excess of alcohol, and leaves them dry and cool enough for 
immediate use. 
2 The use of agar as a substratum for this purpose (Garman and Didlake, 7), and Sphagnum moss, did not 
prove to be satisfactory. Soil, too, has a disadvantage in that it does not show the contaminations as 
readily as filter paper or agar. 
8 An oat sprouter with glass front, heated by a kerosene lamp and costing about $10, makes a good light 
incubator for such purposes when the greenhouse is not conveniently located or the temperature suitable. 
This sprouter is unsuited, of course, to cultures or material requiring a constant temperature. 
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