152 MISSOURI BOTANICAL GARDEN. 
TABLE III. 
SHOWING THE NUMBER OF TYPES OF PROTOZOA AND NUMBER 
OF BACTERIA AFTER SUBJECTING SAMPLES OF 
SOIL TO TOLUOL AND CS, FOR THREE DAYS. 
Types Protozoa'Present Bacteria — Million Per Gram Soil 
rinr.ijrnialale rijninilalale 
Treatment |Chk.| 90711. 0%14.%|.2%|1.% [4.9] OBK-| 261.9% | 4.% |.2% |1.% | 4.% 
Soil S.1....) 7] 3|0]0] 6] 5| 0] 20! 20) 20] 1.6] 28! 1.41 1.0 
emo) at 7/13] st....| & 1132] opal... 31.3|16.3|..... 7.6 
ee st gt] atl a pal] 6 |148| gael... 2:8115.6|..... 23.2 
“wall gf of Tl} 1] 97] 11 54! 73/308] 45] 65 | s.4li196 
we 5] 6] 51 0]0] 4] 2] 2 ]114| 14/41 15-2| 40:0|163| 1701 86 
“ee e} 6] 7/2/01 71 5] 5] 50| 17.41 7.1] 4:8|12:4| 62/5] 27.0 
wu 7] gl47] 7 |...) 48] 5 |....1 13:9 [42.0] sib]... 21.1 |*34.5| .... 
Total Types| 18 | 12] 7 14°) 28 | 101 6 f..c0.|ececsfecevchiccs eee... y, 
T.=toluol; C.=CS2; S.=— sample. 
*By error .3% was added. 
The principal facts brought out in these four tables may 
be summarized as follows :— 
(1) The chemicals studied when applied to soil in small 
quantities exert a stimulative effect upon the multiplica- 
tion of aerobic bacteria, capable of developing upon nutrient 
agar or Lipman’s synthetic agar. 
(2) This stimulative effect may make itself markedly 
evident as early as twenty-four hours after treatment, and 
may remain evident as long as forty-two days—the longest 
trial period—even when evaporation is prevented. 
(3) This stimulative effect is markedly evident with 
01% —the weakest trial quantity—and may be evident with 
4%, there being apparently a wide variation with different 
soils, 
(4) The greatest stimulative effect lies apparently near 
2% for the majority of soils tested, and beyond 1% we 
usually get a decrease. 
(5) The decrease, when evident at 1.%, is nearly as 
marked with that amount as with 20%. 
The above results were at such variance with those 
obtained by Russell and Hutchinson, the only persons, so far 
as the writer is aware, that have made laboratory investiga- 
