14 
Research Bulletin No. I 
Appel and Wollenweber have worked over a great Dumber 
of Fusarium species and made it their first object to determine 
which characters in this genus can be used as general, reliable 
species characters. They also came to definite conclusions con- 
cerning the nature of the medium and the cultural conditions 
which will give these characters most uniformly in their true 
form and have designated these as "normal" because they offer 
each Fusarium the conditions "Bei der er (der Pilz) im Stande 
ist, seinen Entwickelungsgang normal abzuschlieszen." They 
make use of the following characters: form of conidia; presence 
or absence of chlamydospores ; color of the conidia; septation; 
mycelial color; width of the conidia; and absence or presence of 
plectenchyma-like stroma masses. 
They found that boiled potato tubers and boiled potato stems 
furnished a normal substratum when kept at a temperature 
ranging from 12° to 25° 0., and in diffuse light. 
Cultures grown on gelatin and agar media are not normal 
and cannot be used in the determination of characters. For the 
bacteriologist these media have arbitrarily been made normal, 
but for the mycologist Avho works with higher fungi they are 
only of secondary use as Brefeld 1905 points out and as is well 
borne out by the great masses of conflicting data which have 
accumulated around many of our species. It is well known that 
agar colonies often show characters which the fungus ordinarily 
does not show and that more often not all of the characters of 
the fungus are realized on these media. 
The usual host tissue should be used as much as possible as a 
substratum, and descriptions should only be made from such cul- 
tures. Tn fact, there is no reason why the mycologist, who works 
with a vastly more complex mixture than many a chemist does, 
should not adopt the exact methods of description which the 
chemist uses. The bacteriologist already has done this. Thus, 
the normal culture medium for each genus should be determined; 
and then the nature and kind of the medium and the conditions 
of light, temperature, and moisture should be clearly stated with 
each new description of the fungus, so that any one can repeat 
the work and that all work will be done under the same condi- 
tions. This will involve a great deal of labor, but the conditions 
which will enable us to make determinations of reliable characters 
of certain complicated genera will have to be determined before 
much headway can be made. In these studies the characters 
used by Appel and Wollenweber Avere employed and the results 
show that they are reliable characters under the conditions of 
the experiment. It has also been found that all of these charac- 
ters can be modified from the normal by variation in the cultural 
conditions. 
