io64 ABDERHALDEN'S REACTION AND "PROTECTIVE" FERMENTS 



represents the weakest part of the procedure. This point has not been clearly em- 

 phasized in the literature, and yet, undoubtedly, it has been the main cause of non- 

 specific reactions. Until this difficulty has been removed, each test must be preceded 

 by careful titration of substratum. Thus the Abderhalden reaction cannot be adopted 

 as a routine diagnostic procedure, and should be limited to special fields of research, 

 where it will often give valuable information. 



VALIDITY OP THE HYPOTHESIS OF "aBWEHRFERMENTE" 



Quite apart from the difficulties arising from the necessity of establishing quanti- 

 tative relationships between the amounts of substratum and of specific serum in each 

 case, the fact that it is possible in any instance to bring about digestion in the presence 

 of normal serum raises a question as to the validity of the hypothesis of Abderhalden 

 concerning the existence of specific protective ferments (Abwehrfermenic) . If, accord- 

 ing to this hypothesis, the appearance of ninhydrin-reacting substances in the dialy- 

 sate in the case of pregnancy, for instance, is due to the digestion of the placenta sub- 

 stratum in vitro by the specific ferments present in the sera of pregnant individuals 

 only, how then is it ever possible for a male serum to cause similar changes under 

 any circumstances? Moreover, since normal serum thus may apparently exhibit 

 digestive power in one instance in the presence of an excess of placenta, in another 

 in the presence of carcinomatous tissue, and in a third in the presence of tuber- 

 culous lung, etc., as repeatedly reported in the literature, it is necessary to admit 

 either the presence in all of the sera of all sorts of specific ferments, or the opposite— 

 that the apparent digestion in the presence of these various substrata may take place 

 without the co-operation of specific ferments. Besides, the specificity of the ferments 

 responsible for the digestion of the substratum may be questioned also on the basis of 

 the experiments of De Waele,' who succeeded in demonstrating by means of the Ab- 

 derhalden reaction the presence in the blood of the ferments a few minutes after the 

 parenteral introduction of the foreign protein into experimental animals, an interval 

 hardly sufficient for the production of new specific ferments. These results corroborate 

 the previous findings of Heilner and Petri,^ who concluded from the rapidity with 

 which the ferments appeared in the blood after parenteral introduction of foreign 

 protein that this must be a case not of new formation of such ferments, but of 

 activation {Arteinstellung) of some pre-existing ferment. This is also the conclusion 

 reached by a number of investigators who succeeded in demonstrating the presence of 

 proteolytic ferments in normal sera by submitting the latter to adsorption by various 

 substances, such as kaolin, starch, agar, etc.^ However, these findings help to explain 

 only the mechanism by which an excess of substratum might cause activation of the 

 ferments present in a normal serum,'' and throw no light on the apparent tendency 

 toward specificity in the Abderhalden reaction. 



' de Waele, H.: Ztschr.f. Inmiunitdtsforsch. u. exper. Tlierap., Orig., 22, 170. 1914. 



'Heilner, E., and Petri, T.: MUnchen. med. Wchnschr., 60, 530. 1913. 



3 Flatow, L.: loc. ciL; Herzfeld, E.: Joe. cit.; Kjaergaard, S.: loc. cit.; Peiper, A.: Deutsche met. 

 Wchnschr., 40, 1467. 1914. 



< Kjaergaard, S.: loc. cit.; Peiper, A.: loc. cit. 



