170 CHEMISTRY OF THE IMMUXITY REACTIOXS 



toxin,^° and thus causes reactions, but the whole anaphylatoxin ques- 

 tion is in so uncertain a state at the time of writing that further 

 speculation in this direction is not justifiable. 



The attempts to produce antitoxin against cantharidin have not 

 yielded convincing results,-'^ nor against epinephrine.^- De Angelis ^^ 

 claimed that he had produced specific precipitins for various natural 

 and syntlietic dyes, but this woi'k has, as was to be expected, failed 

 of confirmation.^^ Elschnig and Salus "" state that melanin from the 

 eye is antigenic, producing complement-fijiing antibodies specific for 

 melanin but not for the species. We know too little concerning the 

 composition of melanin to interpret this observation; furthermore, 

 their preparation was not tested for proteins. 



In general terms, therefore, antigens are protein molecules, and 

 the reactions of immunity are reactions against proteins foreign to 

 the body of the host, and manifested by the presence in the blood 

 of the reacting animal of substances which combine with and cause 

 recognizable changes in the foreign protein.'" These changes are 

 recognized in many ways, such as precipitation, agglutination, com- 

 plement-fixation, etc., and the question at once arises as to whether 

 these diiferent manifestations depend each upon a separate antibody, 

 or if several or all of them are not caused by a single antibod}^ the 

 action of which is indicated by the different reactions which are made 

 manifest by different procedures in each case. This question will be 

 discussed further in later paragraplis. 



Knowing that the antigens are merely foreign proteins which have 

 been introduced into the body of an animal, there naturally occurs 

 the thought that the animal body is continually receiving in its food 

 foreign proteins, and against which it defends itself in the alimentary 

 canal by enzymatic action, which disintegrates these proteins until 

 they have lost their colloidal character. Logically following this 

 comes the idea that perhaps the reactions of immunity are simply 

 the same or similar disintegrative enzymatic actions, carried on within 

 the blood and tissues to protect the body in the same way against 



30 See Manoilov, Wien. klin. Woch., 1912 (25), 1701. 



31 Champy, Compt. Rend. Soc. Biol., Ifl07 (62), 1128. 

 32Pollak, Zeit. pliysiol. Clieni., 1010 (68), GO. 



33 Ann. di Ig. Sperim., 1009 (19), 33. 



34Takemura. Zoit. Imnuinitiit., 1010 (5), 607. 

 __ 35Graefe's Arch., 1011 (70), 428. 



3C Drew lias found no evidence of antibody formation Ity imnuinii'inti molluscs 

 and ecliinoderms (Jour, of Hyp., 1011 (11), 188), from which ho conchules that 

 the reaction to foreign pioteins is not a imiversal ]iroperty of pmloplasm ; a 

 sweeping generalization which requires more extensive investigation for its es- 

 tablisliiiiciil. ("antacuzenp (('omi)t. Rend. Soc. Biol., 1013 (74). Ill) obtained 

 precipitins l)y iiniiiuni/.ing J'linlliisia itiiimiJlatd witii mammalian blood, but no 

 licmolysins with this or A plirodilr aciilcala and Elcdonc vioschatn. Carrel and 

 Ingebrigtsen (.Tour. Kxp. ]\Ied., 1012 (l.'i), 287) have found that tissues growing 

 iti vitro with foreign blood jjroduce hemolytic antibodies for that blood, indicat- 

 ing that isolated cells can react to antigens by antiliody ]>niduction. 



