go BACTERIOLOGICAL DIAGNOSIS. 
Having obtained a clear view of the bacilli examine 
them for motility and absence of clumps, and see whether 
they are present in proper proportion to the amount of 
fluid. 
If the culture is in good condition the bacilli should 
be seen darting about in all directions, but if the move- 
ment is but sluggish the reaction may still be obtained. 
If the specimen is kept for a short time in a warm 
place or in the incubator the movements will usually 
become more rapid. It is hardly necessary to say that 
when dead cultures are used there will be no move- 
ments of translation, though the bacilli may show 
oscillatory (Brownian) movements. 
The specimen must be searched thoroughly for clumps 
of bacilli, and if these are present the emulsion must be 
filtered through a double thickness of white filter paper. 
This examination for clumps is a most important part 
of the process, and must be attended to whether dead 
or living cultures are in use. 
Next see that the emulsion is neither too thin nor 
too thick. No definite rules can be given, but if there 
are very few bacilli in the field a further supply of 
growth must be added to the stock of emulsion, and a 
further specimen examined. If the bacilli are thickly 
crowded together the emulsion must be diluted with a 
little water and re-examined. 
When you are satisfied that the emulsion is right, 
slide off the cover-glass and drop it into some antiseptic 
lotion ; of course this is unnecessary if dead cultures 
are used. 
2. Making the dilution. You are now about to dilute 
a drop of the serum from the patient with a known 
multiple (in this case thirty times) of its bulk of the 
emulsion which you have just prepared. Todo so you 
