1 8 Society for Experimental Biology and Medicine. 



in a given series of acid solutions has therefore been undertaken, 

 and an effort will be made to extend the observations to the 

 tryptolysis of the same proteins in a given series of basic solutions. 



The speed and extent of both peptolysis and tryptolysis are 

 resultants of conflicting influences. In the case of peptolysis, for 

 example, the hydrogen ions in a given acid solution are always 

 essential and positive factors, whereas the accompanying anions 

 or molecules or both appear, to be, as a rule, non-essential and 

 inhibitory factors. This conclusion is warranted by such results 

 as the following, taken from our records of an experiment in 

 which I gram quantities of fibrin were used in 100 c.c. portions of 

 solution at 40 0 C. : 



A. Control solu- B. Digestive mixtures, containing equal 

 tions (without amounts of pepsin and HC1( m 20), with 

 pepsin). different proportions of H a S0 4 . 



Acid solutions : 



a 



b 



1 



2 



3 



4 



5 



6 



7 



w/ioHCl (c.c.) 



100 





50 



50 



5o 



50 



5o 



50 





w/ioH 2 S0 4 (c.c.) 





100 





10 



20 



30 



40 



5o 



50 









50 



40 



30 



20 



10 ■ 





50 



Total volume (c.c.) 



100 



100 



100 



100 



100 



100 



100 



100 



100 





960 



994 



162 



439 



430 



500 



553 



582 



695 



Gram-atoms of H*, per 1,000 liters. 



94 



116 



48 



62 



73 



85 



96 



107 



61 







m\\o 





m\\oo mj$o 



*'/33 



m\2$ 



w/20 



m\2Q 



That acid molecules are not necessarily inhibitory in peptolysis 

 is shown clearly by the appended results of an experiment similar 

 to the one just referred to, but in which acetic acid was used instead 

 of sulfuric acid. In the mixtures referred to below the dissociation 

 of the acetic acid was slight and negligible : 



A. Control solu- B. Digestive mixtures, containing equal 

 tions (without amounts of pepsin and HC1 (m/20) with 

 pepsin). different proportions of CH 3 COOH. 



Acid solutions : ££1234567 



w/10 HC1 (c.c.) 100 50 50 50 50 50 50 



m\\o CH5COOH (c.c. ) 100 10 20 30 40 50 50 



Water (c.c) 50 40 30 20 10 50 



Total volume (c.c.) 100 100 100 100 100 100 100 100 100 



Weight of residue (mgs. ) 2 961 961 198 194 196 193 187 191 945 



Gram-atoms of H\ per 1,000 liters. 94 1.3 48 48 48 48 48 48*0.9 



Concentration of CH 3 COOH mjlQ w/ioo w/50 w/33 w/25 w/20 w/20 



1 Our data for neutralization precipitates (acidalbumin) and proteoses and peptones 

 are omitted for brevity's sake. They accord with the data for undigested residues. 



2 Our data for neutralization precipitates (acidalbumin) and proteoses and peptones 

 are omitted for brevity's sake here also. They are in accord with the data for undi- 

 gested residues. 



'Although the II* concentration of an w/20 acetic acid solution is approximately 



