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Report OF THE BACTERIOLOGIST OF THE 
WHY USE STERILE MEDIA? 
It may seem strange that we did not propagate the cotton in 
unsterilized media just as would have been done on the farm, and 
then determine the character of the growth in the fluid at the 
stage when it would have been used by the farmer. We did so 
in a number of cases and while we believe the results are in strict 
accord with those presented, we have not laid stress on them for 
the following reasons. ; 
It seemed to us that by cutting off the competition which 
would have existed between the germs in the unsterilized media 
and the germs upon the cotton, the latter have had a much more 
favorable opportunity for development than they could have had 
under farm conditions. 
In unsterile media the milkiness which is relied upon to indi- 
cate the time for using the solution appears promptly, even when 
the cotton is not present. Therefore, no reliable conclusions can 
be drawn from its appearance in unsterile media, when the cotton 
is present. 
A-majority of the colonies which develop from unsterile media, 
to which the cotton has not been added, very closely resemble 
those produced by Ps. radicicola. When the cotton has been 
placed in this unsterile media, a microscopic examination of each 
colony is necessary before it can be said with a certainity that it 
is not Ps. radicicola. This markedly increases the labor of exam- 
ining the plates and to a corresponding degree makes the value 
of the conclusion depend upon the quality of judgment displayed 
in the examination. | 
When using sterile media in our examinations, if all suspicious 
colonies were classed as Ps. radicicola, they would not represent 
a sufficient number in the fluid to be of any value for practical 
purposes. 
DESSICATION OF Ps. RADICICOLA ON COTTON. 
Our repeated failures to obtain satisfactory growth of Ps. 
radicicola from the commercial cotton led us to doubt the viabil- 
ity of the germ. ave 
First test.—A. package of Johnson’s absorbent cotton was pro- 
cured from a local dealer and a layer of the cotton cut into sq. 
cm. blocks. These blocks were enclosed by fives in Petri dishes 
