VOLATILE ANTISEPTICS AND SOIL ORGANISMS. 163 
From this we can draw but one conclusion, 7. e., That 
with the soil studied under the conditions of this experi- 
ment, quantities of CS2 and toluol equivalent to 100 cc. per 
square foot, or 3%, even when stirred in, did not, within 
the first eight days, exert any influence upon the number of 
types of protozoa observed in the soil. 
Field Experiments. 
The same samples of soil that were collected for bacterio- 
logical examinations from the three series of field plats 
given in Tables VII, VIII, and IX were also examined 
for protozoa and the results of such examinations are 
recorded in the same tables. 
From these results the conclusion that CS2 and toluol, in 
quantities of 50 cc. per square foot when applied to the 
soils under study, had no diminishing effect upon the num- 
ber of types of protozoa present seems permissible. Such 
decreases as may appear in certain instances are well within 
the limit of error with the methods used. 
GENERAL DISCUSSION. 
In endeavoring to correlate the results just given with 
those previously reported along the same lines, certain 
difficulties are encountered. First, in regard to the initial 
effect of an application of the chemicals studied. Hiltner 
and Stérmer, and Russell and Hutchinson have reported 
a very marked decrease, the former in field, and the latter 
in laboratory experiments, while the writer, applying the 
same quantities, has always noted either no effect or an 
increase in the number of bacteria present. The same 
investigators noted a subsequent enormous increase, while 
the writer has been unable to detect an increase that could 
not be attributed to the stimulative effect of the substance, 
unless such were added in amounts far exceeding those 
reported as used. If, however, in laboratory experiments 
quantities sufficiently large be used, such a decrease, followed 
by the subsequent increase, will be had. As pointed out 
