532 BACTERIOLOGY. 
or more revolutions per mintue; the threads are thrown 
down. The ‘centrifuged’’ sediment will be found 
to contain most of the bacteria present, epithelial cells, 
and at times spermatozoa. Normal urine on being 
‘‘ centrifuged ’’ at this velocity will be found at times 
slightly turbid at the bottom of the tube. This tur- 
bidity will be found, on microscopical examination, to 
consist of epithelial cells, a few leucocytes, and some 
bacteria. 
Heiman looks upon the decolorization by Gram’s 
method as the only reliable criterion, so far as known, 
for the gonococcus in discharges from. the mucous mem- 
branes, and it is of material help, also, in determining 
whether a culture is or is not that of the gonococcus. 
The careful examination of gonorrheal threads with 
cover-glass by Gram’s method is a very tedious affair, 
as in every instance no less than three cover-glass prep- 
arations should be looked over before the absence of 
the gonococcus is proved. It would require many 
hours upon each and every specimen, especially if the 
gonococci are present in very small number, before a 
reliable and conscientious opinion could be rendered. 
If, after all, a negative opinion is ventured, we still 
are under the necessity of proving that because the 
threads which we fished out for the cover-glass exami- 
nation were free from gonococci the remaining ones 
were also. For this reason the culture medium is more 
sensitive for bacteria than is the cover-glass, for we are 
able to plant each and every thread of the sediment in 
the centrifugal tube. Fiirbringer, in his work, men- 
tions the fact that in certain cases the absence of the 
gonococcus in many examinations of cover-glass prep- 
arations is not a positive proof that the gonococcus is 
