148 Immunity 



corpuscular stroma by filtration or decantation. Two cubic 

 centimeters of it are placed in a small test-tube, and further 

 diluted with an equal quantity of physiological salt solution 

 (if more water be added a precipitate of globulin might 

 take place and spoil the experiment). To such a prepared 

 blood preparation, from six to eight drops of the immune 

 serum are added. If the diluted blood come from the same 

 kind of an animal as that used to immunize the animal 

 furnishing the test serum, immediate clouding takes place, 

 and a flocculent precipitate forms. The precipitate never 

 occurs with any other blood. For those who desire to 

 acquaint themselves with the best technic for the per- 

 formance of experiments with the specific precipitates, we 

 refer the reader to the book of Nuttall mentioned below, 

 and to a subsequent paper by Nuttall and Inchley,* in which 

 an apparatus for the accurate quantitative estimation of 

 the precipitate is described. 



Wassermann and Schutzef prepared a test serum by in- 

 jecting rabbits with human blood, and tested its precipi- 

 tating powers upon twenty-three other kinds of blood and 

 found no reaction except with the blood of a baboon, but 

 the reaction in that case was not nearly so marked as with 

 human blood. 



The most interesting and one of the most important bio- 

 logical applications of this phenomenon is by Nuttall, whose 

 work, "Blood Immunity and Blood Relationship" (Cam- 

 bridge, 1904), should be read by all who wish to study the 

 subject for its scientific interest as a means of determining 

 the blood relationship of animals, or its practical medico- 

 legal importance in recognizing blood-stains. Nuttall 

 conies to the following conclusions: 



" (i) The investigations we have made confirm and extend the ob- 

 servations of others with regard to the formation of specific precipitins 

 in the blood-serum of animals treated with various sera. (2) These 

 precipitins are specific, although they may produce a slight reaction 

 with the sera of allied animals. (3) The substance in serum which 

 brings about the formation of a precipitin, as also the precipitin itself, 

 are remarkably stable bodies. (4) The new test can be successfully 

 applied to a blood which has been mixed with those of several other 

 animals. (5) We have in this test the most delicate means hitherto 

 discovered of detecting and testing bloods, and consequently we may 

 hope that it will be put to forensic use." 



* "Journal of Hygiene," 1904, iv, p. 201. 



f "Deutsche med. Wochenschrift," 1900, No. 30. 



