1902.] STENGEL — SPECIFIC PRECIPITINS. 407 



Samuel Timmins, F.S.A., at Birmingham, England, on No- 

 vember 12, 1902, £et. 76. 



Joseph Miller Wilson, at Philadelphia, on November 24, 

 1902, a3t. 61. 



Dr. Alfred Stengel read a paper on " Specific Precipitins 

 and Their Medico-Legal Value in Distinguishing Human and 

 Animal Blood." 



SPECIFIC PRECIPITINS AND THEIR MEDICO-LEGAL 



VALUE IN DISTINGUISHING HUMAN AND 



ANIMAL BLOOD. 



BY ALFRED STENGEL. 

 i^Read December ^, ig02.) 



Recent studies of the complex problem of immunity have been 

 most fruitful of results, not alone in the direction of explaining im- 

 munity, but also in disclosing a number of phenomena whose bear- 

 ing on the general question is perhaps subsidiary, but whose scien- 

 tific and often practical interest in other directions is highly valua- 

 ble. Among these the phenomenon of precipitation is an important 

 one, and it is to this that I desire to direct attention. Kraus first 

 showed that the serum of animals immunized against cholera causes 

 a flocculent precipitation in the filtrate from cholera cultures, while 

 sera from normal animals produces no such results. Later he 

 showed that this precipitation is specific in the sense that cholera 

 serum produces precipitation in the filtrate of cholera cultures 

 alone, while sera from animals immunized with other cultures had 

 no such result. Subsequent investigations have confirmed and ex- 

 tended Kraus' contribution. The peculiar substance which pro- 

 duces the precipitation in the bacterial culture is probably a product 

 of cell activity made under the stimulus of the immunization, and 

 the precipitable body in the cholera culture is extracted from the 

 bodies of the bacteria themselves. It is seen then that this phe. 

 nomena of precipitation as applied to bacteria is a valuable one in 

 determining bacterial species, but it has not been so employed by 

 bacteriologists, since it is far less easy of application and far less 

 certain in its results than the agglutination test of Gruber, Durham 

 and Widal. 



