498 THE TECHNIC OF COMPLEMENT-FIXATION REACTIONS 



TABLE 20. FORENSIC BLOOD TEST 



2. Complement-Fixation Method for the Identification of Meats. 



The technic is essentially similar to that used in the foregoing test. 

 Antiserums are prepared by immunizing rabbits with the serums of 

 various animals, as the ox, horse, dog, cat, or any other animal the 

 presence of whose flesh is to be identified in sausages, bologna, etc. It 

 is not necessary to immunize with an extract of these meats themselves, 

 as the blood or blood-serums will suffice. The technic of immunization 

 is the same as that employed in the preparation of precipitin serums. 

 Each antiserum is titrated with its antigen, as previously described, 

 and is used in double the titrated dose in conducting the main test. 



An extract of the flesh to be examined is prepared as described on 

 p. 310. 



The test is then conducted in exactly the same manner as previously 

 described. 



3. Complement-Fixation Method for the Identification of Bacterial 

 Antigens. As a means of diagnosis, this test has very limited practical 

 value. It aims to detect, by means of complement fixation with a 

 known antiserum, a soluble bacterial antigen in the blood-serum of a 

 patient. For example, in typhoid fever the patient's serum is mixed 

 with a potent antityphoid serum in the presence of complement. After 



