THE OPSONIC INDEX 



233 





manner equal quantities of control serum, bacterial 

 suspension and washed leucocytes are taken up and 

 mixed in pipette C (Fig. 28, III and IV). The 

 tips are sealed in a flame and the two pipettes incu- 

 bated for a few minutes in a thermostat or opsonizer 

 at 37° C. (Fig. 29). Care should be taken to agitate 



the contents every five min- 

 utes during incubation, 

 otherwise the corpuscles 

 will gravitate and a per- 

 fect admixture of serum, 

 bacteria and phagocytes 

 will not be obtained. At 

 the conclusion usually of 

 fifteen minutes, smears are 

 made of the contents of the 

 pipettes on cover-slips by 

 the usual method or glass 

 slides, employing Kulm- 

 hardt's spreader (Figs. 30 

 and 31). After drying, 

 the smears are fixed in absolute alcohol and stained 

 with freshly filtered carbolthionin or by the method 

 of Homer Wright. In the determination of the 

 tuberculo-opsonic index, the culture of tubercle 

 bacilli is killed by fractional sterilization on three 

 successive days at 100° C, then thoroughly ground 



Fig. 30. — Illustrating the construction 

 of Kuhnhardt's spreader. A shows a 

 glass slide properly nicked by a file; B, 

 the slide p.cpcrly broken in a slightly 

 concave line; C, the broken slide with 

 corners clipper" ; D and E, the perfected 

 spreader spliced to a second slide with 

 adhesive plaster. 



