MICHIGAN ACADEMY OF SCIENCE. 
117 
Fig. 7. — Collecting blood-corpuscles. 
out on to a slide and mix thoroughly (see Fig. 14). Take up the pipette, seal 
the end in the flame (see Fig. 15), and incubate for fifteen minutes. In 
drawing the mixture into the pipette for the final time, care should be taken 
to avoid air bubbles, as these interfere with phagocytosis (see Fig. 17). 
A convenient form of centrifuge for opsonic work. 
In order to get accurately measured portions of the different fluids, the 
usual method is to make a mark with a wax pencil on the capillary portion 
of the opsonizing pipette, about f or f of an inch from the end. Then, by 
means of a rubber nipple on the other end, the blood corpuscles are drawn 
