A STUDY OF FIXATION REACTIONS. 373 



Weichardt(46) and Stranon(47) attempt to distinguish between individuals 

 by obtaining a highly immune serum, determining its exact value, dissolving 

 as much as possible of the antibody with the serum to be tested and finally 

 adding serum from the homologous individual to determine how much antibody 

 remains. Loele(48) finds he has satisfactory results with precipitin when the 

 material used for inoculating his rabbits was preserved with two per cent for- 

 malin in normal salt solution. 



EXPERIMENTAL WORK. 



In two cases we were called upon to determine the nature of suspected 

 blood stains upon some clothing of natives accused of murder. In the 

 first case the accused alleged that the stains were chicken blood. There 

 were minute flecks upon the surface of a cheap khaki garment which 

 had not been absorbed into the fiber. The stains were examined about five 

 months after the murder, having been kept meanwhile in a safe at room 

 temperature. Extracts made with distilled water and subsequent addition 

 of 1.7 per cent salt solution were colorless, the sediment having a dark, 

 brown color. The haemin test, precipitin and fixation tests were all 

 negative, and we concluded that the stains were not due to blood. The 

 fixation and precipitin tests were conducted both with antihuman and 

 antichicken serum. 



In the second case there was a stain on a cheap cotton garment, which 

 measured about 1.5 by 1 centimeter. The stain had penetrated the 

 fiber and gave an extract which was positive for heemin crystals, and 

 which gave excellent precipitin and fixation reactions with antihuman 

 serum. The accused claimed that the blood was from a carabao, but 

 as neither precipitin nor fixation tests could be obtained by using anti- 

 carabao serum with the stain, we made a diagnosis of human blood. 



In this latter case the precipitin test was eminently satisfactory and 

 gave an excellent ring of precipitate in varying dilutions of the extract. 

 The fixation test also yielded excellent results. 



Since in the Philippine Islands and particularly in Manila four races 

 of men, Malay, Mongolian, Caucasian and Negro are represented, it 

 would be of no small importance medico-legally, if we could distinguish 

 between these bloods by means of biologic tests. BruckU 6 ) had already 

 claimed that this could be clone by means of the deflection method, before 

 we undertook these experiments to determine whether either the deflection 

 method or precipitin test furnished sufficiently reliable results for this 

 purpose. 



At the same time a comparison of the two methods was made in the 

 differentiation of the blood of the various species of cows to be found in 

 Manila, 



A number of rabbits were immunized, some against Caucasian blood, 

 others against Filipino, monkey {Cynomolgus philippinensis C4eoff.), chic- 

 ken, and carabao serums. Of the antiserums obtained, one anticarabao 



77S51 2 



