38 
Research Bulletin No. 1 
Graph 1 represents the fluctuation in the number of non-sep- 
tate spores, Graph 2 the fluctuation in the number of one-septate 
spores, Graph 3 the fluctuation in the number of two-septate 
spores, and Graph 4 the fluctuation in the number of three-septate 
spores. Graph 5 represents the fluctuation in the number of 
spore septation of a culture made from the same inoculum as 
cultures of Graphs 1, 2, 3, and 4 and grown on potato stems for 
78 days. Counts were made when the culture was 15, 24, 47, 
and 78 days old. Graph 6 represents the fluctuation in the 
number of spore septation of a culture made from the same 
inoculum as cultures for Graphs 1, 2, 3, and 4, grown on glucose 
agar for 150 days. Counts were made when the culture was 
5, 37, 55, and 150 days old. Graph 7 represents the fluctuation 
in the number of spore septation of a culture made from the 
same inoculum as the culture for Graph 6 and grown on a potato 
>lug for 138 days. Counts were made when the culture was 25. 
39, 65 and 130 days old. 
In Graphs 5, 6, and 7 each space on the abscissa represents 
one day and every two spaces on the ordinate one per cent. 
Lines 0, 1, 2, and 3 represent the number of 0-, 1-, 2-, and 3- 
septate spores respectively. 
From these graphs it is apparent that the number of 1-septate 
spores increases with the age of the culture and that the number 
of 2- to 3-septate spores decreases. This holds for all sorts of 
media and substrata. It also is apparent that light has little 
influence on the percentages, at least not more than the error of 
the count, that moisture has some influence and that temperature, 
especially low temperature, has the most decided influence. Low 
temperatures retard growth, consequently a spore is slowly cut 
off, does not germinate into a hypa at once, but rather grows 
slowly and becomes septate. The multicellular spore is really 
only a slow or delayed form of germination of a single celled 
spore or true conidium. Observations of single-celled spores 
show that they are just as able to germinate as any other. The 
many-celled spores when put into water break up into their 
component parts which can germinate under proper conditions. 
As the food supply becomes exhausted, and this is soon realized 
on the outside of the mat of a colony, the 2- to 3-septate condition 
drops off and the 1-septate condition runs up to 90 to 98 per 
cent. In tubers, when the fungus has sufficient food but 
where a sudden check is put on growth due to desiccation, the 
percentages of non-septate spores run high. The spores ordinarily 
fall off the sterigmata when in the non-septate condition; often, 
however, especially if growth is slow, several septa may appear 
before the spore falls off. Under favorable conditions a single- 
