PRECIPITINS 223 



beef serum, found that the eui>iobulin, pseudoglobulin and albumin 

 fractions could not only be differentiated from each other by the 

 precipitin test but could also be shown to differ from beef hemo- 

 globin. 



Schur (1904) says that Wa.ssermann (1900) deserves the credit 

 for first applying the precipitin test to tlio differentiation of 

 liuman and animal proteins. Uldenliuth (1901) is usually creditod 

 with the introduction of the tcsl as a medicolegal ]U'ocedui'e. 



Early Investig-ations. — Group Reactions.— While Kraus, Was- 

 sermann and even Uhlenhutli at first regarded the test as strictly 

 specific Nuttall (1901) early recognized group reactions. Nuttall's 

 observation was immediately confirmed by Uhlenhuth and others 

 and due allowance made for this in the technical procedures worked 

 out by them. Uhlenhuth 's conclusion that the test is specific, pro- 

 vided the antigen dilution used is at least 1:1,000, has been re- 

 peatedly confirmed and is at tlie present time an integral part of 

 precipitin technique used in medicolegal cases. Closely related 

 species are differentiated by absorption and precipitin tests. 



Value in Tracing Biological Relationship. — Shortly after 

 Wassermann's (1900) observation that the blood of different 

 species could be differentiated by the precipitin test, Nuttall (1901, 

 1902, 1904) investigated the biological relationship within the 

 animal kingdom by means of the precipitin reaction and also recom- 

 mended that it be used in medicolegal cases. In this work he 

 employed not only the routine qualitative procedure but also a 

 new quantitative technique which he had devised. 



It is obvious from a perusal of the early monographs of Nuttall 

 (1904), Kraus (1904), Uhlenhuth (1909) that extensive investiga- 

 tions were conducted relative to precipitins, their formation, 

 nature, specificity, effect of physical and chemical agents upon 

 them, the simultaneous existence of antigen and antibody in sera, 

 the mechanism of the reaction, the importance of precipitins in 

 elucidating various chemical, biological and medical problems, 

 and the source and nature of the precipitates formed in the reac- 

 tion. This is very evident fi'om the following summary of conclu- 

 sions which Nuttall (1904) draws from a survey of the literature 

 and from his ovm experiments. 



