Antibodies in General 11 



The chemical nature of antitoxins has been the subject of con- 

 siderable investigation without much light being thrown on the subject. 

 Brieger and Ehrlich (1893, p. 345) precipitated tetanus antitoxin 

 from the milk of immunihed animals by means of ammonium sulphate, 

 finding that the antitoxin was included in the first precipitate obtained 

 by adding 27 — 307o of the salt. The remaining filtrate still contained 

 much albumin, but very little antitoxin. Freund and Sternberg 

 (1899, p. 432) precipitated diphtheria antitoxin from antidiphtherial 

 horse serum by means of oO^o ammonium sulphate. Seng used 

 magnesium sulphate to saturation, Jacoby (cited by Michaelis 1902, 

 p. 41) found antiricin in rabbit serum to be present in the fraction 

 precipitated through the addition of 25 — o3Yo ammonium sulphate. 

 The antitoxins are therefore precipitated under the same conditions as 

 the globulins, but not the albumins. We shall see that other antibodies 

 behave similarly in this respect. Some authors claim that the antitoxins 

 are identical with the globulins, others that they are only entangled 

 with the globulins, being precipitated under the same conditions. 

 Pick (1902, p. 5) refers the disagreement to differences in the chemical 

 methods used by different authors, and discusses the subject at length. 

 Pick found diphtheria antitoxin in horse serum to be present in the 

 pseudoglobulin fraction, whereas in the goat it was present in the 

 euglobulin fraction. 



Ehrlich (1901, Schlussbetrachtungen, etc.) has sought by means 

 of schematic figures to render our conception clearer regarding the way 

 in which the various antibodies enter into chemical union with different 

 substances, by means of what he terms receptors. Before proceeding, 

 the reader is referred to the figures and description on the succeeding 

 page. 



In normal assimilative processes, as also in the earlier stages 

 of immunization (either artificial or in consequence of disease), the 

 various receptors are attached to the molecule of the cell which is 

 receptive either for the foodstuff, toxin or the like. When the receptors 

 are produced in excess they are thrown off into the circulation. 

 Accepting the above diagrammatic representation of the receptors 

 attached to the cell-molecules as a base, then the freed receptors would 

 be represented similarly, only detached at their base. Such freed 

 receptors have been termed " haptins " ; they possess the same structure 

 as the attached receptors. The haptins corresponding to receptors of 

 the Orders I. and II. have been styled " unicepto/s," those correspond- 

 ing to receptors of the III. Order as " amboceptors," by Ehrlich. 



