188 Keport 8.A.A. Adyanckment of Science. 



conductivity like electrolyte solutions, but ai'e of a negative electrical 

 character, whereby they migrate to the anode ; it is impossible to 

 obtain them in crystals ; their most common peculiarities are their 

 thei-mal susceptibility, their mutability and perpetual and chietly 

 iiTBversible mutation. 



Quantitively the best studied reactions of immune Iwdies are as 

 follows : — 



(1) The neutralisation of the toxines by the antitoxines (Craw). 



(2) The precipitine reaction, i.e. the combination of the precipi- 

 tines with the respective precipitable substances. 



(3) The agglutination or the conglomeration of cells (microbes or 

 blood cells) by the agglutinines. 



(4) Cytolysis, especiall}- ha'molysis, the destruction of microbes 

 by means of bacteriolysines respectively of red blood cells by the 

 hifmolysines. 



All these reactions are more similar to absorptions than to 

 chemical reactions, for they take place in heterogeneous system.s 

 where surface energies, diffusion and electrical forces play a very 

 important role. 



The facts that the law of constant multiple proportions (typical 

 for chemical conjunctions) does not hold good for the reactions of the 

 immune substances, that the addition of one substance in fractions 

 alters the final result (Bordet, Dungern, Danysz), that the typical 

 reaction only takes place when the substances are present in certain 

 optimal concentrations (precipitines and agglutinines), and that they 

 show their typical peculiarities only in company with ions — these facts 

 are direct proofs of the conception of the reactions of the antibodies as 

 colloid-reactions. 



This conception is supported by a great number of analogies 

 Avithin the limits of physical chemistry, from which I need only men- 

 tion the imitation of toxicity experiments of the (toxine-antitoxine 

 compounds) + (toxine) with colloidal As.^So and colloidal Fe(OH)3 

 (Biltz), precipitations of various colloids by each other (electrically 

 different), agglutination and h.ie)nolysis experiments witli chemical 

 precipitates in suspension (Gengou), and artificial colloids (Land- 

 steiner, Henri and Cernovodeanu, Zangger, Frei). 



(rl) The Enzymes. 



Another class of colloidal substances of enoj-mous importance for 

 the life of an organism is formed by enzymes. In principle these are 

 not different from the catalytic substances (Breilig), which possess the 

 peculiarity of altering in a positive or negative sense the speed of a 

 reaction (Ostwald). 



An analogy to the organic enzy)nes are some artificial colloids 

 which act like these, for instance, hydrogen peroxyde is decomposed into 

 H.,0 and by the colloidal metals (Bredig), and by the organic enzymes 

 as'well (Henter). But the colloidal state of a substance alone is not 



