734 
Journal of Agricultural Research 
Vol. V, N 0 . 16 
not suppressing pycnidium formation is always associated with increased 
aerial growth. When it is recalled that with rich media the pycnidia 
are commonly formed in the aerial mycelium, this opposed condition 
may be significant. Further discussion of this behavior is given at 
another place (page 741). 
In conclusion, it may be pointed out that transpiration, or, better, low 
air humidity, is a factor of only secondary or contributing influence in 
fruit-body formation for this fungus, and in no sense is a positive deter¬ 
mining factor like light or aeration. 
Physicochemical Factors 
REACTION OF THE SUBSTRATUM 
The acid or alkaline reaction of nearly all biological fluids—the blood, 
milk, sea water, cell sap—varies but slightly from neutral. It is 
commonly said that fungi grow best under slightly alkaline conditions. 
Many organisms show great tolerance to either alkalinity or acidity, but 
the organism here investigated showed a comparatively narrow range, 
and its optimum point was not that of the great group of fungi, but 
much more like the optimum for bacteria. 
The following experiment with filter-paper cones and with Raulin 
solution shows something of the limits of growth and reproduction for 
this organism. The acidity or alkalinity 1 indicated in the table was 
obtained by the addition of either normal potassium hydroxid or hydro¬ 
chloric acid (potassium hydroxid in case of the Raulin solution, since it 
was acid at the outset). 
Table XIV .—Effect of acidity and alkalinity; Test with Raulin solution and filter 
paper 
[Time, i month] 
Reaction. 
Raulin solution. 
Filter 
paper. 
Number of 
pycnidia. 
Growth. 
Number 
of pyc¬ 
nidia. 
Growth. 
— TO , . 
* Contaminated.... 
None. 
— C . . 
None. 
None. 
0, . . . 
+ 
Strong. 
20 
Scant. 
4 - e... . 
++ 
Strong. 
20 
Scant. 
' 0. 
J_.Tr- 
0 
Fair. 
None. 
! . 
-j-28 . 
0 
Fair.. 
None. 
This experiment showed the strict relation of this organism to the 
chemical reaction, both as to growth and as to reproduction, and, as 
usual, the growth limits were wider than the limits of reproduction. 
The experiment also revealed why Raulin’s solution had previously 
1 Computed in terms of cubic centimeters of normal hydrochloric add or potassium hydroxid in a liter 
by titrating 5 c. c. with NI20 standards, phenolphthalein as indicator. 
