Journal of Agricultural Research 
Vol. V, No. 3 
This was prepared by adding 100 gm. of Penn clay loam soil to i liter of 
a io per cent hay infusion plus 0.5 per cent of egg albumin, which the 
writers had previously found to be best adapted to the large and rapid 
development of protozoa in such soil (6). 
The method of procedure was as follows: The numbers of protozoa in 
the stock culture solution were first counted by the new method described 
in a previous paper (6) and recorded under classes of (1) flagellates, 
(2) small ciliates (12 to 20 /*), and (3) large ciliates (25 to 6 o/jl). No 
amoebae developed in the short period of incubation. Ten c. c. of the 
culture solution were then placed (by means of a sterile pipette) on filter 
paper, previously sterilized with alcohol, and allowed to filter through 
for one minute. The protozoan content of the filtrate was then recorded 
in triplicate and the filtrate incubated for five days at 22 0 C., in order 
to allow the excystment of any encysted forms. The filtration and 
incubation processes were then repeated, if necessary, until all the living 
protozoa of the desired type had been separated out. The filter paper 
was used in from one to five different thicknesses (Schleicher and Schiiirs 
No. 589). The results are recorded in Table I. 
Tabu® I .—Number of protozoa per 10 c. c. of filtrate through varying thicknesses of 
filter paper 
Number of filter papers. 
Sample 
No. 
Number of 
flagellates. 
Number of 
small ciliates. 
12-20/*. 
Number of 
large ciliates, 
25-60/*. 
Total, 
f 1 
106, 250 
537125 
42, 500 
201, 875 
o». 
2 
127, 500 
42,500 
317875 
201, 875 
1 3 
85, OOO 
21,250 
81, 875 
188, 125 
Average. 
106, 250 
38.95 8 
52,083 
197,292 
f I 
63.750 
S3,125 
O 
n6, 87s 
2 
63, 75° 
3 i, 87s 
O 
95,625 
i 3 
74,37S 
3 i, 87s 
O 
106, 250 
Average. 
67,293 
38,958 
O 
106, 246 
I 1 
53 j 125 
317875 
O 
85,000 
S3,125 
21,250 
0 
74,375 
l 3 
737 750 
21,250 
0 
957 250 
Average. 
60, 416 
24, 742 
0 
85, 208 
j 1 
53 > 125 
10, 625 
0 
63,7S° 
3 . 
537125 
10, 625 
0 
63, 75 ° 
l 3 
63, 75 o 
10, 625 
0 
73, 7S° 
Average. 
56, 666 
10, 625 
0 
67,083 
f * 
10,625 
0 
0 
IO, 625 
4 . 
2 
10, 625 
0 
0 
IO, 625 
l 3 
10, 625 
0 
0 
10, 625 
Average. 
10, 625 
0 
0 
10, 625 
5 . 
i 
| None. 
None. 
None. 
None. 
Average. 
a Stock protozoan solution. 
