IMMUNITY REACTIONS 199 



stearic acid, and lecithin, only very little of it is taken up by cetyl 

 alcohol, casein, coagulated serum albumin, and starches (K. LAND- 

 STEINER and A. BOTTERI*) . Arachnolysin is adsorbed more strongly by 

 glacial acetic acid collodion than by formol-gelatin; glacial acetic acid 

 collodion adsorbs rennin very strongly, but adsorbs practically none 

 of a serum containing anti-rennin (H. BECHHOLD* 4 ). Silicic acid and 

 barium sulphate fix complement which, however, is also fixed by 

 kaolin to a lesser extent (E. HAILER*). 



In view of these specific influences, L. JACQUE and E. ZUNZ* un- 

 dertook extensive experiments upon the adsorption of antigens and 

 antibodies by inorganic suspensions. They concluded, as had pre- 

 viously been shown by E. ZUNZ* that differences in surface tension 

 were not alone determinative for adsorption. They found, e.g., that 

 bone black strongly adsorbed diphtheria toxin as well as antitoxin, 

 though neither was adsorbed by wood charcoal, diatomaceous earth, 

 talc, kaolin or clay. Nevertheless kaolin and clay adsorb tetanolysin. 

 Bone black, a good adsorbent for diphtheria antitoxin, does not 

 adsorb the antitoxin of tetanolysin or cobra hemolysin. 



Reversibility. A purely mechanical adsorption demands that the 

 process be completely reversible. This occurs in the case of the 

 slightest adsorptions of immune bodies by unorganized suspensions. 

 W. BILTZ, H. MUCH and C. SIEBERT* have already called attention 

 to the fact that the adsorption of their antigens by hydrogels was 

 only slightly reversible. Only to this extent was J. BORDET'S* com- 

 parison of immune reactions to the dyeing of fiber with dyes appro- 

 priate. This irreversibility has its analogies in the adsorption of 

 numerous other known substances in which we assume that secondary 

 changes occur as a result of the concentration at the surface; some of 

 these changes are chemical, e.g., the adsorption of crystal violet and 

 of rennin by bone black. 



Of great interest are the observations of L. JACQUE and E. ZUNZ* 

 illustrating the competing action of several adsorbents for a single 

 substance. They found that the adsorption of diphtheria toxin by 

 bone black was reversible in the body but irreversible in vitro 

 [probably because of protective substances. Tr.]. The adsorption 

 of diphtheria antitoxin is, on the contrary, irreversible in the body 

 and reversible in vitro. Serum albumin may prevent the adsorption 

 of diphtheria toxin and antitoxin by bone black. 



Adsorption by Organized Suspensions. 



If agglutinin is added to bacteria, or hemolysin to blood corpuscles 

 with the same quantity of the suspension, proportionately more ag- 

 glutinin or hemolysin will be combined from a dilute solution than 



