AGGLUTININS. AGGLUTINOIDS AND PROAGGLUTINOIDS 143 



and Banzhaf 1 and others have found that the sera of horses immunized 

 to diphtheria toxin show a marked increase in globulin content, with 

 a decrease in albumin content. Beljaeff 2 could find no appreciable 

 change in the refractive index, specific gravity, freezing point or 

 reaction of the serum of an immune animal above that of a normal 

 animal. 



The chemical nature of antibodies, aside from their apparently 

 close relation to globulin, has not been determined. There is evidence 

 that antitoxin molecules may be larger than toxin molecules, how- 

 ever. Martin and Cherry 3 found that toxins could be forced through 

 dense porcelain filters impregnated with gelatin, which would restrain 

 antitoxin, and Arrhenius and Madsen 4 determined that the toxin mole- 

 cule diffused several times as rapidly as the antitoxin molecule, from 

 which observation they assumed that the antitoxin molecule was 

 larger than the toxin molecule. 



AGGLUTININS. AGGLUTINOIDS AND PROAGGLUTINOIDS. 



Gruber and Durham 5 appear to have been the first to clearly demon- 

 strate specific clumping in broth cultures of typhoid and cholera 

 organisms when their respective sera were added to them. Somewhat 

 later Widal, 6 and independently Griinbaum, 7 utilized the principle 

 of the specific agglomeration of bacteria by their immune sera for 

 the diagnosis of typhoid fever. They found that relatively early in' 

 the disease, sera of typhoid patients clumped typhoid bacilli from 

 broth cultures. Pfaundler 8 observed that typhoid bacilli grown in 

 broth containing low concentrations of specific sera grew out into long, 

 tangled filaments, the " thread" reaction. Originally this phenome- 

 non was regarded as highly specific, but it has largely given way to the 

 macroscopic or microscopic agglutination test. 



Agglutination in the bacterial sense may be defined as a clumping 

 or agglomeration of bacteria from a uniform suspension in a fluid 

 medium, brought about by the addition of specific antibodies 

 agglutinins. It takes place in two stages if motile bacteria are con- 

 cerned. First there is loss of motility "immobilization" and 



1 Jour. Exp. Med., 1910, xii, 411. 



2 Cent. f. Bakt., Orig., 1903, xxxiii, 293, 396. 



3 Proc. Royal Soc., 1898, Ixiii. 



4 Festskrift Statens Serum Institute, 1902. 

 6 Munchen. med. Wchnschr., 1896, No. 13. 



6 La Semaine Medicale, 1896, No. 13. 



7 Brit. Med. Jour., 1897, May 1, and Munchen. med. Wchnschr., 1897, 330. 



8 Cent. f. Bakt., 1898, xxiii, 9, 71, 131. 



