ZONATION IN ARTIFICIAL CULTURES OF CEPHALOTHECIUM 
AND OTHER FUNGI. 
BY GEORGE GRANT HEDGCOCK. 
The results given in this paper are from a continuation 
of the investigation, mention of which was made in a brief 
paper to the American Mycological Society at the Phila- 
delphia meeting, December, 1904, and are published by 
permission of the Secretary of Agriculture. 
Certain fungi like Cephalothecium, Penicillium, Mucor 
etc., often exhibit in artificial cultures a distinct zonation 
of the mycelium due to denser masses of spores being 
formed daily on certain portions of the mycelium, often 
giving an agar plate culture the ringed appearance of a 
target. Last year it was proven by a set of experiments 
that daily variations of temperature are not the cause of 
this zonation. At the same time it was shown that they 
were not produced under conditions of total darkness, but 
occurred only in cultures grown in the light. 
In order to determine what colors of light affect spore 
formation, cultures of . Cephalothecium, Penicillium, 
Mucor, and Hormodendron were grown on agar plates 
under five conditions of light. Double bell jars of ordinary 
glass were filled with solutions as follows: for orange light, 
potassium bichromate; for red, a cochineal solution; for 
blue, a mixture of ammonium and copper carbonate; for 
green, a mixture of * anilin gelb’’ and ‘* licht griin;’’ for 
ordinary light, a double bell jar without a solution; and 
for darkness, a tight, black-lined box. No spectrum anal- 
ysis of the rays of light transmitted by some of these solu- 
tions has yet been made. 
The cultures grown under red and orange light, and in 
darkness, exhibited a uniform dense spore formation over 
the whole surface of the mycelium in every instance. 
The cultures grown under blue light and in ordinary 
light, in every instance exhibited distinct daily rings of 
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