Studies on So-Called Protective Ferments. 7 



of serum globulin seems to promote the appearance of dialyzable 

 substances, probably on account of the digestion of the globulin 

 by the serum ferment. 



5 (937) 



Studies on so-called protective ferments. V. The serum is the 

 source of dialyzable substances. 



By J. Bronfenbrenner. 



[From the Pathological and Research Laboratories of the Western 

 Pennsylvania Hospital, Pittsburgh, Pa.] 



In the experiments related above I have shown that the serum 

 of a pregnant individual, placed in contact with placenta at 0° 

 temperature and separated from the placenta by subsequent 

 centrifugation, is capable of giving up dialyzable substances if 

 placed in the incubator. Assuming that the cells of placenta were 

 centrifuged down, the only explanation for the appearance of 

 amino acids and polypeptids in such a serum was that the serum 

 acquired the ability to digest itself. The fact that the addition of 

 fresh placenta to such serum does not increase the degree of 

 dialysis on the one hand, whereas on the other addition of serum 

 globulin increases it very markedly — points toward the correctness 

 of this assumption. 



Some experiments conducted in my laboratory at present with 

 placenta as well as with bacterial substrata will prove definitely 

 that the substratum is not the source of dialyzable substances in 

 the Abderhalden test. While these experiments are still in 

 progress, I tried also to see if my assumption of the auto-digestion 

 of serum in the Abderhalden test will hold good in the case of 

 syphilis, for if the dialyzable substances should appear in this 

 case, there will be no doubt as to their source, as the substratum 

 in this case is not of protein nature. 



As it was to be expected, the sera of syphilitics, when brought 

 into dialyzing thimble with suitable amount of pure lipoid, often 

 gave positive Abderhalden test, while sera of normal individuals, 

 treated in similar way gave most often negative results. The 

 adjustment of the amount of lipoid to be used in this test is very 



