166 



LABORATORY COURSE IN SERUM STUDY 



taken up by the leucocytes, and that the serum constituent 

 which carries out such preparatory action is comparable to other 

 antibodies. The property of the serum which carries out this 

 preparation of the bacteria for phagocytosis has been spoken of 

 by Wright as the opsonic power, since he supposed it to depend 

 upon a specific antibody, which he called opsonin. In immune 

 sera this phagocytosis-aiding antibody is more heat-resistant 

 than it is in normal sera, and such a heat-resistant immune body 

 is spoken of by the Wright school as the immune opsonin and by 

 Neufeld and his associates as bacteriotropin. 



Serum. Obtain normal guinea pig serum by bleeding two pigs 

 from the carotid into centrifuge tubes and separating serum. 



Leucocytes. Wash out peritoneum of two guinea pigs injected in- 

 traperitoneaHy with 6 c.c. of aleuronat suspension about 8 to 12 

 hours before. Take 2 c.c. of suspension, centrifugalize, wash the sedi- 

 ment once in saline and suspend in saline until emulsion corresponds in 

 thickness to standard tube prepared by instructor. 



Bacteria. Make suspension of staphylococcus aureus from agar 

 culture in salt solution until thickness corresponds to standard tube. 

 Draw in and out of capillary pipette until the bacteria are evenly 

 emulsified. Allow clumps to settle and pipette off upper layers. 



Experiment 1 



OPSONIC ACTION OF SERUM 

 Set up three tubes as follows : 



All tubes are incubated one half hour at 37 C. Two smears are 

 then made of the sediment on slides and stained by Gram's method, 

 or with Jenner's stain. To obtain material for smears pour out the 

 supernatant fluid and scrape the leucocytes from the bottom of the tube 

 with a platinum loop. The bacteria in a hundred consecutive leucocytes 

 on each slide are then counted. 



