PRECIPITINS. 67 



bodies found in bacterial cultures had previously 

 been shown by Kraus. 



Nature of the Precipitins. The precipitins are 

 fairly resistant bodies, whose power gradually de- 

 clines at a temperature of 60 C., but is not lost until 

 70 C. is reached. The resulting precipitate is solu- 

 ble in weak acids and alkalies. Peptic digestion 

 destroys the substances which effect the precipita- 

 tion. Concerning the chemical nature of the pre- 

 cipitins, we have an admirable study by Leblanc, 

 who finds in the case of a large number of precipi- 

 tins that they are precipitated with that fraction of ^ 

 the serum which Hofmeister calls the pseudo-globu- 

 lins. The pseudo-globulins constitute that part of 

 the total globulins which is soluble in distilled 

 water, while the rest, the euglobulins, are insoluble. 

 The nature of the resulting precipitate has also been 

 studied by Leblanc. He finds that it is a combina- 

 tion of the precipitated albumin with the anti-body, 

 a pseudo-globulin, of the specific serum. In this 

 combination the properties of the pseudo-globulin 

 predominate, showing that it is the specific serum ^ 

 which furnishes the greater part of the precipitate. 



Action Not Entirely Specific. Of special interest 

 is the inquiry as to how far the action of these pre- 

 cipitins is specific. The first experiments of Bordet 

 had shown that the specificity is not complete ; that 

 the serum of rabbits injected with chicken serum 

 is a precipitin not only for chicken serum but 

 also for that of pigeons. The author and Schutze, 



