208 
THIRTEENTH REPORT. 
SOIL FUNGI. 
A PRELIMINARY REPORT OF FUNGI FOUND IN AGRICULTURAL SOIL.* 
LI. N. GODDARD. 
INTRODUCTION. 
It is well known that a great amount of work lias been done in recent 
years, on the bacteria of the soil, and their importance is recognized. 
However, comparatively little attention has been given to soil fungi, and 
little is known of their influence on plant growth. 
This investigation was begun about a year ago, in the botanical labora- 
tory of the University of Michigan, under the direction of Prof. J. B. 
Pollock. The purposes especially in view were the following: First, to 
determine what species of fungi live habitually in an ordinary agricul- 
tural soil; second, to ascertain their distribution as to depth and kinds 
of soil, and third, to find what part they take in soil fertility. 
A plat of rather rich clay loam, having a liberal amount of sand, was 
chosen for investigation. Samples of this soil were taken and cultures 
made in the laboratory by the usual plating method. From these, pure 
cultures were isolated and studied. 
CULTURE MEDIUM. 
The medium selected for the platings was chosen largely with refer- 
ence to the idea of inhibiting the growth of bacteria, which would seri- 
ously interfere with the study of the fungi. For this purpose, two meth- 
ods were tried. First, a large per cent of gelatin was added to the me- 
dium; and second, the medium was made strongly acid by the use of 
oxalic or lactic acid. The latter method was largely a failure and was 
abandoned on account of the frequent liquefaction of the medium after 
addition of the acid. The first method was fairly successful, and was there- 
fore employed, throughout the investigation. The only difficulty in its use, 
was a tendency with the salts used, to get a precipitate during the ster- 
ilization. This occurred much less by three successive sterilizations in an 
ordinary steam sterilizer, than in an autoclave. By the former method it 
was possible to get a fairly clear medium which worked well. Practi- 
cally no bacterial growth was observed upon it. The full composition of 
this medium was as follows: 
Gelatin 30.0% 
Agar 2.0% 
Monopotassium phosphate 0.2% 
Ammonium nitrate . 0.2% 
Magnesium sulphate 0.02% 
The acidity of this medium was tested by the method in common use 
among bacteriologists, described by Dugger (1) in his recent book. This 
♦Contribution No. 128 from the Botanical Department of the University of Michigan. 
