8 THE MICROSCOPE. 
with aniline blue (“package” blue answers) in glycerine not too 
deep in color, one minute, and wash with water. When well dried 
mount directly in balsam. When well stained a good 4th or 4th in. 
objective shows the bacilli well. 
HOW TO MAKE A SECTION OF TOOTH WITH PULP. 
F. O. JACOBS. 
HARD section of a tooth with pulp can be prepared by the 
following method: 
As soon as the tooth is extracted it should be immersed in 
alcohol and kept there until you are ready to begin work. To do 
the work you should be prepared with a polishing lathe, and emory 
wheels, such as dentists use. The wheels should be about five 
inches in diameter and three-fourths of an inch thick, also a small 
felt wheel for pad to hold the section while cutting. 
One emery wheel should be very coarse to do the first cutting 
rapidly, then a medium, and for the finishing wheel made of the 
finest flour of emery. 
Begin work by holding the tooth to the circumference of the 
wheel with the thumb and finger of each hand. Cut down the tooth 
on each side until you see the pulp, sliding the tooth back and forth 
across the wheel so as to grind evenly from the crown to apex of the 
root. Keep the wheei wet all the time with plenty of distilled 
water. The tooth should now be returned to the alcohol and kept 
there a short time, say for half an hour. When you begin cutting 
again use the flat surface of the same wheel cutting one side, then the 
other until your section is about one-eighth of an inch thick. Now 
use the next finer wheel, and go from that to the finest for the final 
polishing, returning the section to alcohol occasionally for a few 
minutes so as to keep the pulp as hard as possible. Use the felt 
wheel as a bed for the section while grinding. Keep a good tooth 
on your emery wheels by washing in alcohol and rinsing in pure 
water before the alcohol dries. 
Cut the tooth one side then the other alternately so as to insure 
your taking the section from the center of the tooth; otherwise the 
pulp will tear out, and the canaliculi shows better from this portion 
of the tooth. 
When the section is as thin as desired, it should be carefull 
