MICHIGAN ACADEMY OF SCIENCE. 
209 
gave an acidity of 80+ , according to Fuller's (1) scale. The inhibiting 
effect on bacterial growth appeared to be due to this rather strong acid 
quality. 
METHOD OF SAMPLES, PLATINGS AND ISOLATIONS. 
The method of taking the soil samples, was a modification of that used 
by King, at the Kansas Agricultural Experiment Station, in bacteriolog- 
ical work. The sampler and other instruments were sterilized over an 
alcohol flame, immediately before use each time. Samples of 2 c.c. each, 
were taken and transferred to sterile, cotton-stoppered test tubes, which 
were then taken to the laboratory and each treated with 18 c.c. of sterile, 
distilled water. After thorough shaking, 3 drops were transferred from 
each by means of sterilized pipettes, to the first of a series of three 
tubes, each containing 10 c.c. of the nutrient medium. From the first 
tube, 3 drops were transferred to the second and from the second, 3 
drops to the third. Plates were then poured in the usual way. Vigorous 
growth was generally obtained in from three to four days. When indi- 
vidual mycelia were distinguishable, pure cultures were isolated to cul- 
ture tubes. An agar medium, similar in composition, but without the 
gelatin, was usually employed for these pure cultures, since the gelatin 
medium was found to liquefy easily, especially in warm weather. Little 
difficulty was encountered in getting pure cultures in this way. That 
the method of plating was successful in keeping out all foreign spores, 
was demonstrated bv a set of blanks, which was made at the time the 
other plates were poured. These were poured like the others, but were 
inoculated from sterile, distilled water. On these no fungi developed 
until many days after liberal growth had occurred on the soil inoculated 
plates, and then, only an occasional mycelium appeared on the very edge 
of the plate. In most cases, these blanks were perfectly clear for weeks 
after their preparation. 
PROBLEMS OF STUDY. 
As suggested in the introduction, these fungi were now investigated 
with reference to the following problems: 
1. Distribution as to depth. 
2. Distribution as to kind and treatment of soil. 
3. Structural characters and identification. 
4. Power to assimilate atmospheric nitrogen. 
It is the purpose of this paper to present a preliminary report on the 
first three of these only. The fourth will be reserved wholly for a later 
publication, in which the results of the entire investigation will be pre- 
sented in final form. 
DISTRIBUTION AS TO DEPTH. 
The plat selected for experiment, was a piece of garden soil, which had 
been in use for many years for raising common vegetables, usuallv in 
rotation. It had been heavily manured as a rule, but during the last 
three or four seasons, this had been less frequent and less abundant. No 
manure had been used the year preceding the investigation, although a 
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