PRECIPIT1NS 113 



The reliability of this reaction in medico-legal 

 questions has been abundantly established. In the 

 forensic blood diagnosis the subjects of the test 

 are usually blood stains on clothing, and on wood 

 and metal objects. After such a doubtful stain 

 has been dissolved in physiological salt solution, 

 one first proceeds to determine that it is really 

 blood. For this purpose Teichmann's test (the 

 production of ha3min crystals), the guaiac test, and 

 the spectroscopic examination are undertaken. This 

 is of considerable importance, for not merely blood 

 but other albuminous solutions derived from the 

 same animal react with an antiserum obtained by 

 injecting an animal with blood or serum. Having 

 found that the stain is that of blood, we next deter- 

 mine the special kind of blood. 



Immunizing the Animals. For the production of 

 the antisera, we make use of rabbits. These can be 

 injected either with sterile, freshly-defibrinated blood 

 or with sterile serum, the latter being preferable 

 for intravenous inoculation. It is well to begin 

 with small doses and gradually increase; thus for 

 intravenous inoculations the first injection should 

 be about one c.c. and increased up to three or 

 four c.c. With intraperitoneal injections about 

 double these doses can be given. Ordinarily, the 

 interval between injections is three or four days, 

 and the entire duration of treatment from two 

 weeks to a month. Long-continued treatment 



