Dec. 13.19 is 
Activity of Soil Protozoa 
481 
sampling. In order to ascertain whether the soils contained cysts of 
protozoa which would become active when conditions became favorable 
after they had been examined, the soils collected at the third sampling 
were water-logged with sterile tap water and allowed to stand in the 
laboratory for 40 hours, when they were examined for motile protozoa. 
(See Table II.) 
Table II .—Extent of protozoan activity in field soils under different conditions of 
moisture a 
Lab¬ 
ora¬ 
tory 
No. 
Kind of soil. 
Soil treatment. 
Normal 
moisture 
content. 
Moisture 
content 
two days 
after 
heavy 
rain. 
Moisture 
content 
five days 
after 
heavy 
rain. 
Presence of active pro¬ 
tozoa when soil sam¬ 
ples were water¬ 
logged. & 
Per cent. 
Per cent. 
Per cent. 
1 
Shale. 
Bare. 
25. 07 
13 - 73 
22, OX 
21. 73 
14. 18 
S.C.ttt F.t 
S.C.ft F-tt 
2 
Sandy loam. 
Orchard. .. 
18. 66 
3 
Gravelly sandy 
loam. 
Garden.... 
9. 62 
12.40 
8. 60 
S.C.fF.t 
4 
Clay loam. 
Orchard. .. 
15 - 14 
19. 18 
12. 72 
S.c.t F.t 
5 
Gravelly clay... 
Meadow. .. 
15-67 
20. 10 
15.21 
S.C.ttt L.C.t F.t 
6 
7 
Clay loam. 
Silt loam. 
Wheat. 
19.65 
II. 22 
17. 30 
15. 24 
16. 08 
14. 88 
9 - 3 8 
14. 62 
S.c.t 
S.C.tl 
S.c.t- 
L.C.t F.t 
1* F.t 
1 * L.C.t F.t 
8 
.do. 
Weeds. 
13. 42 
9 
Sandy. 
Com. 
II. 34 
14. 88 
II. 25 
S.C.tl 
•F.tt 
10 
Gravelly silt 
loam. 
Fallow. 
10-93 
14. 28 
10. 58 
S.C.tl 
fF.t 
11 
Shale. 
Bare_... 
19. 88 
23. 36 
20. 27 
S.C.ttt L.C.t F.t 
12 
Gravelly silt 
loam. 
Wheat. 
9. 60 
* 5 - 5 i 
8.97 
S.c.t F.t 
13 
14 
Silt loam. 
Com. 
10. 90 
6. 74 
15.66 
12.18 
10.95 
8. 52 
S.C.tt F.t+ 
Do. 
Sandy loam. 
Vetch and 
tomatoes. 
° Under normal conditions and two and five days after a heavy rain no active protozoa were observed. 
& S. C.=small ciliates; L. C.*= large ciliates; F.=flagellates; A.=amebse; f=few; several; ttt=many. 
The careful examination of the 14 soils in no case revealed any motile 
protozoa, indicating that under the normal and even somewhat abnor¬ 
mal conditions of moisture active protozoa did not seem to be present 
in the soils examined. Several samples of standing rain water were 
collected when the second and third samplings were made. Upon 
examination all of the samples of water showed the presence of many 
small dilates and flagellates, which indicates that the protozoa are 
active in accumulated water. In all cases where the 14 soils were 
water-logged small ciliates and flagellates, and in some cases even large 
dliates, were present in the active state. The data presented in Table 
II point to the fact that all ordinary soils contain cysts of protozoa, 
and in the 14 soils examined the active organisms were not observed 
until sufficient moisture was present. It would seem that if the pro¬ 
tozoa did become active when the moisture content was higher than 
it was at the time of the first sampling after the heavy rain, they re¬ 
mained active but a very short period of time, as in no case were they 
