494 
Journal of Agricultural Research 
Vol. XI, No. i© 
bedded were noticeable on the end of the beak. These droplets gradually enlarged 
and finally overflowed the pycnidium, coalescing with similar droplets from other 
pycnidia and thereby forming an almost continuous liquid covering of the substratum. 
A stroma was not formed on stems of Melilotus alba. In this particular experiment 
no stylospores were formed. In other cultures, however, of the same organism on 
M. alba stems a few stylospores were found. 
EFFECT OF LIGHT ON GROWTH 
The literature is full of the records of experiments on the effect of light 
on growth and development of chlorophyll-bearing plants, as well as 
fungi. It would be useless to review all or any considerable part of these 
records here. It is evident, however, from a perusal of some of these 
publications that no general, sweeping conclusions can be drawn that 
will apply to all fungi alike. Recent results, on the other hand, show that 
under similar conditions individual fungi may be expected to respond 
differently. In support of this last statement, reference may be made 
to the results of Coons (10), who found that light was a determining factor 
in the production of pycnidia with Plenodomus fuscomaculans (Sacc.) 
Coons. The writer (19), on the other hand, working with a different 
species of Plenodomus, P. destruens Harter, found that the absence of 
light did not inhibit the production of pycnidia. That the absence of 
light very greatly inhibited, but did not entirely prevent, the production 
of pycnidia by Diaporthe batatatis , was shown by Harter and Field (21) 
in another experiment. The writer has obtained similar results, as yet 
unpublished, with other fungi. 
The influence of light on growth and production of fruiting bodies of 
the pycnidial stage of Diaporthe phaseolorum was determined by inocu¬ 
lating stems of Melilotus alba in test tubes and exposing one-half of the 
set to light and excluding the light from the other tubes by wrapping 
with black paper, which was found by previous test to prQhibit the 
passage of light. The tubes were all tightly plugged with cotton. The 
cotton plugs alone were left exposed, so as to permit aeration. The two 
series were then placed on a table in the center of the laboratory room 
and kept under observation for 25 days. The cultures began to dry up 
about that time and development was accordingly arrested. The tubes 
kept in the dark were examined for a few minutes every few days for 
the purpose of taking notes and were for that length of time exposed 
to the light. While this brief period can not be regarded as having 
no influence on the results, exposure to the light for such a short time 
would certainly have no marked effect. The growths of mycelium in 
the cultures in the light and those in the dark were about the same at 
the end of three days, but from that time the mycelial growth in 
the dark was relatively more abundant and more cottony. In tubes 
in the light, on the other hand, there was, as has always been, a minimum 
of mycelium on stems of Melilotus alba. At the end of six days pycnidia 
