20 
Research Bulletin No. 1 
in cultures in 1 per cent glucose solution and in distilled water. 
In the former case there probably is so much food that the 
mycelium can maintain its growth without going over to spore 
formation, while in the latter the growth is so slow and im- 
poverished that septation cannot set in. 
Spores are borne on conidiophores of varying complexity. 
Generally the conidiophores are arranged on one side of a hypha 
and are simple, unbranched, one to several celled, sterigma-like 
structures. A compound tristerigmate conidiophore has been 
found, and all gradations between this and the simplest have 
been obtained by varying the cultural condition. 
The fungus on its natural host makes a loose growth and 
takes the form of an aerial mycelium when it has access to cavi- 
ties. Before the cavities are entirely filled, and in moist tube 
cultures, the peculiar arrangement of the hyphae which puts this 
fungus under the Tuberculariaceae is very apparent. 
No sporodochia-like structures are found on agar at all. At 
times on agar, especially if a little normal lactic acid has been 
added to it, a slimy Pionnotes appearance is realized. This has 
also been found off and on on glucose agar. 
SPORE SEPTATION. 
Counts of spores and measurements were made from cultures 
all of which had been started from the same spore and grown 
under various environmental conditions. All of the detailed 
study was made with the progeny of a single, three-septate, 
curved spore. This course was adopted only after the writers 
had satisfied themselves from studies of colonies which had come 
from 50 single spores that they all behaved alike. It makes no 
difference whether a single celled spore is used or a three-sep- 
tate spore, the results are the same. A three-septate curved 
spore was used so that the variations which do appear might be as 
apparent as possible and because there can be no doubt that such 
a spore is a true Fusarium spore. 
These studies were made with cultures which were grown on 
potato plugs in an incubator, temperature 25° to 27° C. (humidity 
98 per cent), wrapped in black paper, in a refrigerator, tempera- 
ture 8° to 10° C, (humidity 60 per cent), wrapped in black paper, 
in the room in diffuse light, and in the room, wrapped in black 
paper, temperature 20° to 25° C, (humidity 40 to 60 per cent). 
From these cultures counts were made every week for four weeks 
to determine the fluctuation of the number of septations per spore. 
These results are plotted in curves, Tables 2 to 5, Graphs 1, 
2, 3, and 4. Besides these tabulated counts, several hundred were 
made from cultures on potato plugs, agar, and raw potato, and 
