Oct., 1922] YOUNG AND BENNETT FUNGI IN CULTURE MEDIA 46I 
Coons (2),^ working with Plenodomus fuscomaculans, recognized that 
a medium favorable to vegetative growth is not necessarily conducive to 
sporulation. He found it necessary to develop two solutions, one inducing 
mycelial development and the other favoring spore production. 
In a general way all the above mentioned solutions are similar. Em- 
phasis is most frequently placed on the source of carbon. In no case is 
there given a method for the arranging of the proportions and concentra- 
tions. The presence or absence of any one of the inorganic constituents 
depends upon whether the investigator considered it important for the 
growth of the particular fungus under experimentation. Most discussion, 
however, has centered around the roles of calcium, iron, and zinc. 
Molisch (9) is of the opinion that calcium is not necessary for the normal 
development of fungi. While this fact is based on little experimental 
data, it has been generally accepted. 
Currie (3) has concluded that the exclusion of iron is without effect on 
the growth of Aspergillus niger. Other investigators have found that, 
although iron and calcium may not be elements essential for growth, they 
unquestionably exert a beneficial effect on the growth of many fungi. 
More recently the work of Steinberg (14) has shown that in the case of 
Aspergillus niger, zinc has a very decided stimulative effect on the quantity 
of fungus produced. He states that one reason that zinc has not previously 
been used in such media is that sufficient amounts were dissolved from the 
glassware to supply this need. This same statement might well be made 
in the case of iron and possibly in that of some of the other essential in- 
organic elements. 
It is worthy of note that nearly all the synthetic solutions now in general 
use have been formulated on the basis of the food requirements of strict 
saprophytes, in most cases with Aspergillus niger, a fungus that is not at 
all selective but will grow on an exceptionally wide range of media. More- 
over, the name Aspergillus niger as used by different investigators repre- 
sents rather a group of related fungi than one species. For these reasons, 
a study of the role of any salt cannot be safely made when such types of - 
fungi are used as criteria. 
^ Coons' cheap synthetic solution: 
Magnesium sulphate 1.23 g. 
Potassium acid phosphate (monobasic) 2.72 g. 
Potassium nitrate 2.02 g. 
Maltose 7.2 g. 
Water 1000. cc. 
Coons' synthetic solution: 
Magnesium sulphate i cc. of ilf/5 solution 
Potassium acid phosphate 5 cc. of lf/5 solution 
Asparagin i cc. of M/5 solution 
Maltose 5 cc. of solution 
Water 50 cc. 
