94 LABORATORY COURSE IN SERUM STUDY 



9 and 10 must belong to group 3. It is interesting to note that of the two 

 patients who have haemolysins in their blood, patient T has haemolysins 

 only affecting the one group (presumptive group 3 Nos. 7, 8, 9 and 10) 

 and agglutinins affecting the other group (Nos. 3 and 5), while patient 

 E has not only agglutinins but haemolysins affecting both groups. This 

 illustrates the fact that there are two hemolysins as well as two agglu- 

 tinins and that the groups of the hemolysins parallel those of the. ag- 

 glutinins. 



The class needs : 



Heavy glass tubing 7-8 mm. diameter. 



Heavy glass tubing 4-5 mm. diameter. 



Litre 1 per cent sodium citrate in 0.6 per cent sodium chloride. 



Litre 0.9 per cent sodium chloride solution. 



Triangular files. 



Rubber nipples to fit 5 mm. tubing (one nipple for each student) . 



Hard paraffine in casserole. 



LESSON XIV 

 TITRATION OF PRECIPITATING SERA FROM RABBITS 



SPECIFICITY OF PRECIPITINS 



PRECIPITATING sera are active against proteins in high dilu- 

 tions. Their specificity is great but is limited by group reactions 

 so that a precipitating serum for the protein of any species of 

 animal or bacteria will give precipitation with closely related 

 species in low but not in high dilutions On this is based Nuttall's 

 well-known study of blood relationships. 



Students working in groups bleed serum-treated rabbits (Lesson I) 

 from the carotid 10 days after the last injection, taking about 20 c.c. 

 of blood in small centrifuge tubes. The animal should be in a fasting 

 state in order that the serum will be clear. Allow the blood to clot and 

 centrifugalize. 



Experiment 1 



One half of the students in the class make dilutions in large test 

 tubes of sheep serum or human serum respectively (according to par- 

 ticular serum with which rabbit has been treated) as follows : 1-10,1-20, 

 1-50, 1-100, 1-200, 1-500, 1-1000. In order to test the specificity of the 

 reaction the other half of the students make similar dilutions of serum from 

 other species of animal guinea pig, dog, cat, sheep, horse, as available. 



