150 MISSOURI BOTANICAL GARDEN. 
the dish. This composite sample was again thoroughly 
_ mixed and several smaller quantities removed, and from this 
lot, after a second thorough mixing, the final weighing 
was made. Weighing was done on analytical balances, a 
sterile piece of paper being placed upon the pan; and in 
every instance, one gram of soil was taken. The gram of 
soil was at once removed to a 125 ec. rubber-stoppered 
Erlenmeyer flask containing 99 cc. of sterile water. This 
was shaken vigorously three times for one-third minute 
each, and while still in motion 1 cc. removed, by means of 
a sterile pipette, to another water blank. This process was 
continued until the sample was so dilute that a Petri dish 
containing 1 ec. could be counted. Duplicate platings were 
made of the final dilution, using approximately 8 ce. of agar. 
At first, standard nutrient agar + 1 was used, but this was 
soon replaced with the synthetic agar proposed by Lipman. 
Cultures were incubated at room temperature until maximum 
counting development was attained. With nutrient agar 
the period was usually three days; with Lipman’s synthetic 
agar one week. Counting was done with a x10 hand lens; 
and if duplicates varied widely, they were discarded. Only 
averages are given. 
In all, twenty samples of soil have been subjected to 
“one or all of the three chemicals mentioned for periods 
varying from one day to six weeks. The samples repre- 
sent soils from rich garden, orchard, forest, lawn, green- 
house, and pasture. 
Table I contains a summary of all samples tested, while 
Table IT contains a very conservative illustration of actual 
results. Table III contains the results of seven samples 
analyzed after being subjected to different quantities of CSe 
and toluol for three days. Table X contains complete results 
of the twenty samples tested. 
