PRECIPi TINS. 69 



and found that this, while not strictly specific so far 

 as closely related species are concerned, is yet so 

 against other species. The precipitins, therefore, 

 react on closely related albumins, but are absolutely 

 specific against those of unrelated species. 



Wassermann's Method of Differentiating Albumins 

 To Test Blood Stains. As a result of these re- 

 searches the author proposed ,. at the Congress for 

 Internal Medicine, 1900, to use these sera as a means 

 of differentiating albumins, i.e., to distinguish the 

 different albumins from one another and particu- 

 larly to distinguish those derived from man from 

 those of other animals. This proposal thus to use 

 the Tsistowitsch-Bordet precipitins had important 

 practical and theoretical results. Uhlenhuth, Was- 

 sermann, Schutze, Stern, Dieudonne, and others 

 showed that a serum could be produced from rab- 

 bits by injecting them with human serum, by means 

 of which it is possible to tell positively whether a 

 given old, dried blood stain is human blood or not. 

 The procedure is as follows: The suspected clot is 

 mixed with a small quantity of normal salt solution 

 and then filtered. To some of this in a test-tube 

 about the double the amount of the specific serum 

 (derived as above) is added. The specific serum is 

 first, however, tested as to its activity. As a con- 

 trol test we place a little blood of another species, 

 e.g., of an ox, in a second test-tube together with 

 some of the specific serum and a little normal salt 

 solution. In a third test-tube we place some of the 



