TECHNIC 



199 



named in their order in the capillary tube from above 

 downward, one volume of blood-cells, an air-bubble, 

 one volume of bacterial emulsion, an air-bubble, and 

 one volume of serum (Fig. 48). 



3. By making gentle pressure on the teat these 

 are then blown out on the surface of a clean glass 

 slide, and perfect mixture effected by making alter- 

 nate aspiration and expulsion from the capillary tube 

 at least six times (Fig. 49). 



4. Carefully reaspirate into the capillary thread, 

 so that the mixture occupies about the middle, and 

 seal the tip in a low Bunsen flame (Fig. 50) . 



5. Remove the teat, and with the wax-pencil mark 

 the tube with the name or number of the serum. 



6. A similar preparation is prepared with the 

 pooled serum (control). 



7. The phagocytic mixtures are then placed in 

 an incubator at 37 C. for fifteen minutes, except in 

 the case of such bacteria as the Bacillus typhosus 

 and the Bacillus coli, as lysin and agglutinin may 

 be present in the serums of such bacteria when the 

 period is reduced to ten minutes. The special 

 opsonic incubators built to accommodate individual 

 pipets are particularly serviceable. 



8. The tubes are then removed from the incuba- 

 tor, the teats readjusted, the tip of the capillary 

 threads scratched with a file, and evenly broken off. 

 The phagocytic mixture is carefully expelled on a 

 clean glass slide, and a perfect mixture made by 

 alternate aspiration and expulsion. Avoid air- 

 bubbles. The whole is then reaspirated, and a 

 small drop of the mixture placed on each of two clean 

 slides that have been roughened with emery paper 

 about % inch from one extremity. With the edge 

 of a spreader slide held at an angle of about 30 

 degrees, and with moderate pressure, the drop is 

 distributed evenly along about 1J/2 inches of the 

 surface of the slide (Fig. 51). The smears are made 

 in duplicate, because one may be more nearly 

 perfect (Fig. 52) than the other, or one may be 





FIG. 48. CAPIL- 

 LARY PIPET FOR 

 OPSONIC INDEX DE- 

 TERMINATION. 



