838 
Journal of Agricultural Research 
Vol. XXX, No S) 
2. Mycelium: With the exception of 
Eupionnotes, in which im¬ 
mersed growth of the myce¬ 
lium predominates even under 
normal and favorable spore 
production, changes to an 
immersed gelatinous growth 
in general indicate degener¬ 
ation and self-digestion ac¬ 
companied by abnormal spore 
production or even sterility. 
This condition maybe changed 
into the norm by transferring 
to various media or by selec¬ 
tion of virulent aerial colonies 
from new agar plates. For¬ 
tunately the number of Fu- 
saria showing a tendency to 
degenerate seems to be small. 
This tendency is notable in 
Fusarium nivale (Fr.) Sacc., 
F. anthophilum (A. Br.) Wr., 
F. orthoceras App. et Wr., 
and F. flocciferum Cda. The 
latter two fungi if inoculated 
into living potato tubers, 
thoroughly disinfected with 
formaldehyde, regain their 
normal behavior when re¬ 
isolated and retransferred to 
sterilized media. In some 
cases, agar media too rich in 
sugar or too alkaline or acid 
in reaction favor degeneration. 
Conditions, however, that fa¬ 
vor-normal conidial production 
generallv warrant longevity 
and sufficient constancy. On 
the same medium mycelium 
transfers often give only a ster¬ 
ile stroma, while a transfer of 
macroconidia increases the 
tendency to reproduce this 
stage. These facts if not 
fully understood may make 
the proper identification of cer¬ 
tain species doubtful. They 
show the necessity of im¬ 
proving cultural methods. 
Brown and Horne (?) in their studies 
of the genus Fusarium have given 
interesting details on the modifying 
effect of transfers from various parts 
of a given fungus. These authors have 
stated that the rate of spread of certain 
colonies fell off after a time and was 
reduced (staling), while other colonies 
developed into normal sporodochia or 
pionnotes with small and low septate 
or long and high septate conidia. Fur¬ 
thermore, “saltants” showing sectorial 
effects of some strains have been pro¬ 
duced in Fusaria derived from six dif¬ 
ferent isolations from apple. In the 
preliminary studies this wide range of 
variability was considered to be con¬ 
nected with one and the same fungus, 
F. blackmani Brown et Horne. 
This variability of the mycelium and 
spore character has been found to 
occur with various fungi. Notable 
among these are two closely related 
Fusaria described as F. anguioides 
Sherb. and F. anguioides var. caudatum 
Sherb. (5). These two organisms are 
closely related to F. anthophilum (A. 
Br.) Wr. isolated from apple fruit in 
England. The abnormal variations 
found in these cases, though great, 
were not mentioned in the diagnosis 
of the Fusaria because normal charac¬ 
ters were regarded as sufficient for de¬ 
termination. 
PRODUCTION OF THE NORM 
Cultural conditionswhich will produce 
good mycelial growth are not necessarily 
those most favorable for the production 
of normal spores. In the study of Fusar¬ 
ium it has been found necessary to 
use a variety of media for the pro¬ 
duction of the various normal mycelial 
and reproductive' stages. The best 
media for these purposes at present 
available are the ordinary ones used in 
plant pathology investigations. A 
combination of a number of vegetable 
substances may prove valuable in 
some cases, but, so far, sufficient work 
has not been done to Justify recom¬ 
mending such a medium. Because the 
same vegetable under different con¬ 
ditions varies in its chemical compo- 
position, it would be highly desirable 
to produce a satisfactory synthetic 
medium. It is hoped that a synthetic 
nutrient may sometime be found 
which will render it possible to control 
the production of spore bodies or 
sclerotia at will. Until some such new 
media are produced, vegetable media 
will be found to be fairly satisfactory 
for taxonomic purposes. 
No one culture medium is at present 
used which will produce optimum 
development of all phases of fungus 
growth; hence certain media have been 
selected which proved most satisfac¬ 
tory for the best production of eonidia, 
and other media for the production of 
sclerotia, mycelium, chlamydospores, 
and other characters. It must be 
understood, however, that not all 
species will react in exactly the same 
way, and therefore a medium which 
produces normal conidia in most 
species may need to be supplanted by 
another in the case of other species. 
The media used at the conference are 
given in Table I. 
