38 



LABORATORY COURSE IN SERUM STUDY 



In measuring 0.05 and 0.1 c.c. of complement it is best to use a half 

 c.c. and one c.c. of a 1-10 dilution. Shake each tube thoroughly when 

 all the reagents have been added. Incubate one hour in water bath at 

 37 C. and record by + or signs haemolysis at 15, 30 and 60 minutes 

 in the following protocol : 



Indicate what the unit is in this case. 



The tabulation given for final record is the manner in which an 

 experiment of this kind is best recorded by experienced workers. We 

 have inserted the simpler protocols of the three series before this in 

 order to make the purpose of this experiment and its execution a little 

 more easy. 



(On account of the costliness of guinea pig serum students should 

 divide themselves into groups of 3, of whom each student should set 

 up one series of amboceptor dilutions with one of the complement 

 quantities.) 



Individual guinea pigs vary in the complementary activity of 

 their serum. For accurate hsemolytic experiments, however, it 

 is necessary to use a constant amount of complement activity. 

 For this reason the unit of amboceptor (which if carefully pre- 

 served remains constant over long periods) is taken as a standard 

 to which the strength of each fresh complement serum is 

 adjusted. 



Strictly speaking, the unit of complement should be that 

 amount which gives complete laking with one unit of cells and 

 one unit of amboceptor. In practice, however, this turns out to 

 be too large an amount, and for this reason complement is usually 

 titrated with two units of amboceptor. Set up titrations with 

 both two and one units as follows : 



