93 2 
Journal of Agricultural Research 
Vol. V, No. 20 
It is the above statement which has stimulated and formed the basis 
of the experimental work recorded herein. No progress has been made 
in the direction of an explanation of the nature of this slime. Its effect 
on the prolongation of the life of micro-organisms subjected to desicca¬ 
tion has been the object in view. 
EXPERIMENTAL STUDY 
An experiment was conducted to determine whether an organism may 
receive protection from the solution in which it is suspended before being 
subjected to desiccation in sand. For this work were used cultures of 
P . radicicola grown for five days at room temperature on nitrogen-free 
ash agar. For suspension the following solutions were employed: 
(1) Physiological salt solution. 
(2) Physiological salt solution + 0.1 per cent of agar. 
(3) Physiological salt solution + 0.1 per cent of gelatin. 
(4) Physiological salt solution + 0.1 per cent of albumin. 
(5) Physiological salt solution + 0.1 per cent of gum arabic. 
(6) Physiological salt solution + 0.1 per cent of soluble starch. 
With the exception of the albumin solution these were all prepared by 
dissolving 1 gm. of the dry substance in a small amount of salt solution 
and then making it up to a volume of 1,000 c. c. They were found to be 
practically neutral to phenolphthalein. On account of the difficulty of 
dissolving powdered egg albumin it was found necessary to use raw 
white of egg, a quantity being taken which by computation contained 
1 gm. of albumin. As albuminous solutions may be heated to ioo° 
without coagulation if slightly alkaline, this solution before steriliza¬ 
tion was made — io° F. S. by the addition of N/r sodium hydroxid. 
After sterilization (which with all six was accomplished by the Tyndall 
method, 30 minutes heating in flowing steam on four successive days) 
the N/i sodium hydroxid was neutralized with N/2 hydrochloric acid, 
leaving the albumin solution like the other five, practically neutral. 
Suspension of the bacterial growth from four agar slopes was made in 
250 c. c. of each of the above solutions. For the purpose of securing 
initial counts 1 c. c. of each suspension was diluted and plated on nitrogen- 
free ash agar. Twelve flasks of quartz sand were then inoculated from 
each of the six solutions, 5 c. c. to a flask. The sand had been prepared 
after the method described by Rahn (19). It was heated with diluted 
hydrochloric acid, washed several times, first with tap water and then 
with distilled water, heated on a water bath until almost air dry, and 
then heated at least 30 minutes over a free flame. Fifty gm. of the dry 
sand was placed in 100 c. c. Erlenmeyer flasks, which were plugged with 
cotton. Sterilization was accomplished by heating for 45 minutes in the 
autoclave under 15 pounds’ pressure. 
The inoculated flasks were kept in a dark, well-ventilated place at a 
temperature of 22 0 to 25 0 C. At intervals the number of organisms per 
