756 
Journal of Agricultural Research 
Vol. V, No. 16 
The results given in Table XXVII show in striking manner the effect of 
the transfer of mycelium from one concentration to another. When myce¬ 
lium from a poor solution is placed in a rich solution, it begins to grow 
vigorously, and, on the other hand, when rapidly growing mycelium is 
transferred to a solution of less concentration, the increase in growth 
is less. Exactly as the mycelium is checked or started into growth, 
reproduction is fostered or inhibited. While from the results of the 
experiments reported before it could only be said that these conditions 
of growth and reproduction occurred constantly side by side and there¬ 
fore were related. From this last experiment we have definite proof of 
the interrelation of these two processes. 
Other factors than food supply were experimented upon in the same 
way. The experiment previously reported under temperature (p. 726) 
strictly speaking belongs here. It may be remarked that pycnidium pro¬ 
duction began in the cold before it began in the cultures under room 
conditions. A similar experiment was performed with com broth. 
Com grains with mycelium about two weeks old, which showed no signs of 
pycnidium production, were set near a window at room temperature, and 
in the light in a cold attic where the temperature was about io° C. 
After one week there were many pycnidia in the culture in the cold and 
the growth was checked, while in the culture under room conditions 
pycnidia production was just beginning and growth had continued 
regularly. After two weeks, however, the pycnidia were abundant in 
all the cultures, but were more abundant in the cultures under room 
conditions. From this experiment it is seen that a checking of growth 
by other means than food withdrawal can operate in much the same 
favorable way upon reproduction. 
If, then, the factor light, which is known to have a strong power of 
checking growth, operates in influencing pycnidia production in this 
manner, we should be able to replace the light effect by checking the 
mycelial growth in some other way. Cultures, if left in the dark, ought 
to produce pycnidia eventually. Cultures with scanty food supply, 
such as those on filter paper, ought to yield pycnidia rather quickly in 
the dark. The experiments already reported have failed to show this 
action. Therefore, the action of light is not merely due to the checking 
influence which it has upon mycelial growth. If it were, we should 
have the paradoxical condition in which the withdrawal of light from 
a culture with limited food supply would augment pycnidium production, 
because of the greater growth in the dark and the more rapid diminution 
of the nourishment. 
The following experiment (see Table XXVIII) was performed, in 
which the effect of checking the growth of corn-broth cultures by low 
temperatures was tried in both light and dark conditions. Corn-broth 
cultures 12 days old were placed under the conditions shown in the 
