742 
Journal of Agricultural Research 
Vol. V, No. 16 
the fact that the corn grain is not extremely soluble, accounts very well for 
the appearance here. Instead of the corn grain furnishing nutrition, the 
corn grain soon becomes the location where food supply is soonest ex¬ 
hausted. In this behavior upon drying, we may also find the explana¬ 
tion of the behavior of the wet and dry bell jars reported in Table XIII. 
The behavior of the i X and % X concentrations of the synthetic medium 
may be considered in this connection. It seems that in this case we 
have a similar factor to deal with. The mycelium in these concentra¬ 
tions grows at the top of the solutions, a trifle submerged in the case of 
the weaker solution. The stronger mycelial growth in the higher con¬ 
centration leads to the formation of a thicker surface film in it than in 
this weaker one, and the film starts much sqoner. The pycnidia are pro¬ 
duced upon this surface film, which, no doubt, in some ways interferes 
with the utilization of the food supply. 
From this it would seem that the limiting concentration suggested— 
M/ioo for sugar—instead of being too low is doubtless too high, and the 
production of pycnidia at this concentration, at the period stated, is 
brought about by the other factors, which lead to an even greater reduc¬ 
tion of the available concentration. 
When we consider the action of this aerial life of the mycelium in fos¬ 
tering reproduction, we find that our knowledge of the transfer of mate¬ 
rials in mycelium is extremely limited. It, however, seems very likely 
that with the increase in concentration in the medium below and the 
drying of the threads, the diffusion of foodstuffs to the aerial parts is 
interfered with. 
quality op pood 
Minerals. —The work with the quantity of foodstuffs just outlined indi¬ 
cates the extreme difficulty of determining what minerals are essential for 
growth. This sensitiveness to extremely small amounts, which doubtless 
is paralleled by other organisms, makes experimentation with ordinary 
methods or ordinary chemicals unreliable. The problem of determining 
the necessary mineral elements for this fungus would be impossible with 
our present technic. 
An attempt was made to find the effect of certain chemicals when they 
were added to various nutrient solutions. Although many experiments 
were performed, the results were so masked or influenced by the constit¬ 
uents of the medium that no conclusions could be drawn. Notable in¬ 
fluences which have been explained as other than nutrition effects have 
been obtained with acid phosphates and with calcium compounds. 
The behavior of one chemical, magnesium sulphate (MgS 0 4 ), is worthy 
of record. Since Molisch’s accurate work (1894), this substance has 
generally been regarded as essential in fungous cultures. The following 
experiment suggests that the chemical may have a profound effect upon 
fructification. Two preparation dishes each received 10 c. c. of a solution 
