162 MISSOURI BOTANICAL GARDEN. 
examined microscopically. If examined earlier than twenty- 
four hours, the particles of soil held in suspension inter- 
fered with the examination. Examinations were continued 
at intervals for at least a week. It was found useless to 
examine the cultures in media under one week’s incuba- 
tion as the same types appeared there as in water cultures. 
After the first week such cultures were examined at inter- 
vals for two weeks. Often the cultures in media were so 
overrun with one or two types that development of other 
types must have been inhibited. A summary of results 
obtained thus far is given in Table ITI. 
Where a “type” is spoken of, it simply means that those 
organisms were so different morphologically that they could 
be easily distinguished under the microscope from the other 
“types” observed. In some instances the term “type,” as 
here used, undoubtedly includes two or more species. Some 
of the more common types appearing have been recognized 
as Amoeba, Colpoda, Vorticella, Strombidium, and Dileptus. 
In some instances, a rotifer and nematode are included, but 
since these organisms do not encyst they should be more 
sensitive to such substances, hence their inclusion should 
not invalidate the results obtained. The letters a-b, etc., 
in Table VI refer to “types” and show their presence fol- 
lowing different treatment. 
From this it appears: (1) That in the seven soils studied 
CS2 and toluol in a strength of .2% do not exert a diminish- 
ing effect upon the number of types of protozoa present; 
(2) That in strengths of 1.% and 4.% the chemicals studied 
do exert a slight diminishing effect upon the number of types 
present, but that several types (7 with toluol 1.%, 4 with 
toluol 4%, 10 with CS2 1.%, and 6 with C82 4.%) are 
able to withstand these strengths. 
Greenhouse Experiments. 
The same samples taken from greenhouse plats as 
referred to in Table VI, taken eight days after treating, 
were also examined for protozoa and the results of this 
examination are recorded in the same table. 
Faia 
