96 



LABORATORY COURSE IN SERUM STUDY 



Then set up the following mixtures in small " precipitation " tubes 

 (tubes of about 5-8 mm. diameter) : 



In making these mixtures, put the anti-serum into the tubes first 

 and then run the dilution into the tubes with a nipple pipette in such a 

 way that the latter is layered over the former as in a Heller's test 

 for albumin in urine. This is the so-called "ring test." The precipitum 

 shows as a white line at the contact of the two fluids. After this ring 

 has formed, the tubes can be shaken up and the ordinary precipitin reac- 

 tion (i.e. turbidity and flocculation) can be observed. Note the results 

 after one half hour and one hour at 37 C. and again after 12 hours in 



the ice box. 



Is there a "pro zone"? 



Experiment 2 

 EFFECT OF HEAT ON PRECIPITINS 



Heat slowly inactivates precipitins. They cannot be reactivated 

 by fresh serum (alexin, complement), in this regard differing from 

 hemolysins and bactericidal antibodies. 



Heat 0.5 c.c. of precipitin serum for two hours at 60 C. Mix 

 0.1 c.c. of the heated serum with 0.1 c.c. of that dilution of the antigen 

 which was found in Experiment 1 to give the optimum precipitation. 



Mix 0.1 c.c. of the heated serum with 0.1 c.c. of fresh normal rabbit 

 serum and test this mixture also with the optimum dilution of antigen. 

 Make observations after 1 hour at 37 C. and again after 12 hours in ice box. 



For each student : 



2 c.c. Immune serum (rabbit whose preparation was begun in 



Lesson I). 

 1 c.c. Antigen serum (human or sheep serum for half the class, 



other animals' sera for the other half) . 

 Salt solution 

 12 Precipitation tubes. Test tube rack. Nipple pipette. 



6 one-c.c. graduated pipettes. 

 0.1 c.c. normal rabbit serum, fresh. 



