96 The Nature of Precipitin Reactions 



On the Nature of Precipitins and Precipitable Substances. 



The power of precipitation possessed by antisera does not appear to 

 depend upon any alteration in the usual physical properties of a serum, 

 for Beljajew (1902) has found no difference in the specific gravity, nor 

 in the alkalinity between these and normal sera. Whitney (1902) 

 claims that a powerful antiserum clotted more slowly than a weak one, 

 a statement which requires confirmation. 



The nature of precipitins has been the subject of considerable 

 investigation, as will appear from what follows. Nolf (v. 1900, p. 300) 

 treated rabbits with (a) washed blood corpuscles, and (6) the serum of 

 the fowl and dog, and found precipitins only in the blood of the rabbits 

 treated with serum, or with "plasma 1 ." He next found that he could 

 produce precipitins in animals treated with globulin solutions, those 

 treated with albumin solution giving a negative result. Artificial 

 globulin solutions gave as good results in this respect as did normal 

 sera. Subsequently Myers (14. VII. 1900) produced antisera for sheep 

 and ox bloods by injecting their serum globulins into rabbits, and Stockis 

 (v. 1901) obtained antisera by globulin injections. Leblanc (31. v. 1901, 

 p. 359) injected different components of ox blood (serum albumin, 

 pseudoglobulin, haemoglobin) into rabbits and found the precipitins in 

 the pseudoglobulin fraction of the immune serum. According to 

 Leblanc the precipitins are pseudoglobulins, or bodies precipitated 

 together with these. Eisenberg (v. 1902, p. 308) on the other hand 

 found the precipitins in the euglobulin fraction of the serum of rabbits 

 treated with horse serum. Strube (12. vi. 1902) cites the results of 

 Corin, Modici, and Biondi as pointing to the precipitins being bound to 

 the globulins. It appears doubtful however whether the globulins them- 

 selves exert the precipitating action (Biondi) if we rely on analogous 

 studies upon the antitoxins, in which Dieudonne (Arb. a, d. kaiserl. 

 Gesundheitsamte, xni) found in the case of diphtheria antitoxin that 

 precipitation with C0 2 yielded antitoxin-free globulins, whereas precipi- 

 tation with magnesium sulphate, as practised by the above observers 

 for the precipitins, caused antitoxins to be carried down with globulins 

 mechanically. Biondi considers the precipitins possess a fermentative 

 action for the reason that he found different amounts of antiserum added 

 to equal amounts of serum to yield no markedly different quantities of 

 precipitum. We have however seen that there is every evidence in 



1 Ide (1902), and Dubois (1902, p. 692) state they have since obtained precipitins 

 by injecting haemoglobin solutions and intact blood corpuscles respectively. 



