The Agglutinins 125 



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. 



Wassermann and Schutze prepared a test serum by inject- 

 ing rabbits with human blood, and tested its precipitating 

 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 

 comes to the following conclusions: (i) The investigations 

 we have made confirm and extend the observations 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." 



The injection of the precipitinogenic serum into animals 

 results in the formation of anti-precipitins by which their 

 activity is neutralized. 



II. Agglutination. This phenomenon was first observed 

 by Charrin and Roger* in the course of some experiments 

 with Bacillus pyocyaneus. They found that the bacilli 

 * "Compte rendu de la Soc. de Biol.," 1899, p. 667. 



