262 FERMENTS AND ANTIFERMENTS 



lipoidal solvents or saturation with various organic and inorganic 

 substances, as boiled tissue, iodin, starch, kaolin, and the like, protease 

 activity is released, followed by digestion, not of the so-called substrat 

 but of the protein of the serum. Likewise Plaut, 1 Peiper, 2 Friedman 

 and Schonfield, 3 and Bronfrenbrenner 4 have obtained positive Abder- 

 halden reactions with guinea-pig and human sera not only with placental 

 tissue but also with such inert substances as kaolin, starch, barium sul- 

 phate, chloroform, etc. These studies would, therefore, tend to show 

 that the boiled placental tissue in Abderhalden's reaction is not digested, 

 but acts simply as an absorbent in a purely mechanical manner. 



Furthermore, Heilner and Petri 5 and de Waele 6 found the ferments 

 in the blood-serum so quickly after the parenteral introduction of the 

 protein, at intervals hardly sufficient for the elaboration of new and 

 specific ferments, as to support the theory that the ferments are pre- 

 formed and that the substrat serves to activate these rather than bring 

 about the production of new ferments. 



The researches of Van Slyke and his associates, 7 employing Van 

 Slyke's method of amino nitrogen determination, have shown that 

 practically every serum, whether from a pregnant or non-pregnant 

 individual, showed protein digestion when incubated with placenta 

 tissue prepared according to Abderhalden; further evidence of non- 

 specificity was seen in the fact that carcinoma tissue was digested 

 apparently to about the same extent as was placenta. Hulton, 8 working 

 with isolated and purified proteins, found no digestion with the sera of 

 injected rabbits in excess of that which took place with the sera of normal 

 control animals, concluding that there is at present no reason for believing 

 that the normal hydrolysis of the protein of the body occurs in the circu- 

 lating blood, but that these metabolic changes presumably belong to 

 the tissue cells. 



It would appear, therefore, that the original theory of Abderhalden 

 is untenable in that specific proteolytic ferments in the blood are not 

 produced during pregnancy, and that the Abderhalden reaction is not 

 due to the digestion in vitro of specific antigen by specific ferments. 



1 Munch, med. Wchnschr., 1914, Ixi, 238. 



2 Deut. med. Wchnschr., 1914, xl, 1467. 



3 Berl. klin. Wchnschr., 1914, li, 348. 



4 Proc. Soc. Exper. Biol. and Med., 1914, xi, 90. 



5 Munch, med. Wchnschr., 1911, Ix, 1530. 

 6 Ztschr. f. Immunitatsf., orig., 1914, xxii, 31. 



7 Jour. Biol. Chem., 1915, 23, 377. 



8 Jour. Biol. Chem., 1916, 25, 163. 



