Dec. 13, 1915 
Activity of Soil Protozoa 
485 
ratory. Examinations were made from time to time for a period, and 
then the samples were placed outside in the open air where the tempera¬ 
ture variation was great and examinations were again made. (See 
Table V.) 
Table V .—Presence of active protozoa in water-logged soils, under constant and variable 
temperatures 
lab¬ 
ora¬ 
tory 
No. 
Kind of soil. 
Presence of protozoa when incubated at room temperature on—a 
May 25. 
June 4. 
June 7. 
1501 
1502 
iS ©3 
1504 
1505 
1506 
Greenhouse. 
.do. 
Field. 
.do. 
S.C.fL.C.f. 
S.C.ttt LC.tt F.ttt 
S.C ftt F.tt. 
S.C.tttL.C.f F.tt- - .. 
S.C.ttt F.t. 
S.C.ttt A.t. 
S.C.ttt L.C.t F.ttt... 
S.C.ttt F.tt. 
S.C.tt F.tt. 
S.C.tt F.tt. 
S.C.ttT. 
S.C.ttt L.C.t F.t. 
S.C.t L.C.t 
S.C.ttt F.tt 
S.C.ttt F.t 
S.C.tttt. F.ttt 
S.C.ttt 
S.C.ttt 
Lab¬ 
ora¬ 
tory 
No. 
Kind of soil. 
Presence of protozoa when incubated at outdoor temperature on—a 
June 8. 
June 16. 
June 23. 
1501 
1502 
1503 
1504 
1505 
1506 
Greenhouse. 
.do. 
Field. 
.do. 
.do. 
s.c.t 
s.c.ti 
s.c.tl 
S.c.ti 
S.c.tl 
s.c.ti 
L. C.t. 
tL.C.tF.t. 
S.C.t L.C.t F.t. 
S.C.ttt L.C.tt. 
s.c.tlt. 
S.C.ttt L.C.tt. 
S.C.ttt . 
S.C.ttt F.tt. 
S.C.t F.t 
S.C.t F.t 
s.c.t 
SC.t F.t 
S.C.tt F.t 
S.C.tt F.t 
aS. 0."= small ciliates; L,. C.=large ciliates; P.=flagellates; A.^amebae; f=few; ff= several; ftt= many. 
The data given in Table V indicate that living protozoa were always 
present in all of the water-logged soils during incubation at outside 
temperature as well as at room temperature. It was noted that the 
sudden change from the room temperature to the outside temperature 
did not have any marked effect upon the existence of the organisms in 
the active condition. 
PERIOD OF EXCYSTMENT OF SOIL PROTOZOA 
Since active protozoa were not found in normal field soils, the question 
at once presented itself, How long a period of time was required for 
soil protozoa to become active in the presence of sufficient moist¬ 
ure, as, for instance, during a heavy fall of rain, and How long will 
they remain in the active state ? In his work with Colpoda cucullus 
Goodey (3) in 1913 found that at 30° C. many were active after an hour. 
It was suggested by Martin and Lewin (8), as previously noted, that 
they may become active in a few minutes. To prevent misunderstand¬ 
ing as to the presence of motile protozoa in the soil, the writer in his 
method of examination proposed a 2-minute examination of each sam¬ 
ple—i. e., the soil was in contact with free water no longer than two min¬ 
utes at each examination. In no case during the entire course of the 
many examinations of field soils were any protozoa noted to have excysted 
