398 



SCIENCE 



[N. S. Vol. XXXVII. No. 950 



have practical significance? Several lines 

 of enquiry may be followed to find an 

 answer to this question, three of which are 

 comparatively direct: (a) the fate in the 

 body; (&) the action on digestive ferments; 

 (c) the action with reference to general 

 health and metabolism. 



(a) With reference to the relations 

 under (a) we have already sufficient in- 

 formation. Small amounts of benzoic acid 

 are completely united with glycine, and 

 for 500 milligrams 307.5 milligrams of the 

 latter are required, an amount far within 

 the liberation from the ordinary protein 

 metabolism. In the cases of infants or 

 invalids with lower metabolism the possible 

 benzoate ingestion is naturally far below 

 this, and there would doubtless be always, 

 €ven in such extreme cases, a sufficient 

 glycine content for combination. 



"With no benzoic acid ingested the larger 

 part of the glycine would probably go to 

 form urea and other products by oxidation. 

 With the benzoic acid we have the synthe- 

 sis of hippuric acid. Unfortunately, we 

 have no reliable means of comparing the 

 magnitude of or the difficulty in the en- 

 zymie work in the two cases. In certain 

 quarters much has been said about the 

 over-burdening of the kidneys with this 

 work of synthesis. As a matter of fact 

 there is no warrant whatever in the as- 

 sumption that the tax on the organism is 

 any greater in this case than in the other, 

 and those who make the assumption prob- 

 ably overlook the fact that the hippuric- 

 acid synthesis in the human body is normal 

 and constant. Because of a lack of deli- 

 cacy in the methods employed for the de- 

 termination of hippuric acid the quantity 

 of this substance excreted daily has usually 

 been greatly underestimated, or neglected 

 entirely. 



(6) The behavior of benzoic acid toward 



digestive ferments has been the subject of 

 several investigations. In this direction 

 the action on diastases, pancreatin, pepsin, 

 rennin and the lipases has been studied. 

 A number of such studies have been car- 

 ried out in my own laboratory, with the 

 general result that while there is naturally 

 an inhibition of digestive activity with cer- 

 tain concentrations of benzoic acid, with 

 those concentrations which have practical 

 importance in the present enquiry the in- 

 hibition is very slight or does not appear 

 at all. 



In the case of the digestion of starches 

 there is indeed a distinct acceleration in 

 the rate of digestion, as is caused by a 

 number of neutral salts and acids of low 

 concentration. This is true not only of 

 digestions by means of malt infusions, but 

 also in the case of taka-diastase and a num- 

 ber of the pancreatic diastase preparations 

 in general use in this country. Similar 

 results were reported some years ago by 

 Leffmann.* 



While 0.1 per cent, of sodium benzoate 

 added to egg albiunin mixture, such as is 

 used in the official pepsin tests, distinctly 

 retards the rate of digestion, this is not the 

 case with one fifth of this concentration, 

 which is probably above the limit ever 

 found in the stomach after the ingestion of 

 benzoated foods. This relation has been 

 observed in a number of mixtures of fibrin 

 as well as egg albumin, and with a variety 

 of pepsin preparations. Analogous results 

 have been reported by Gerlach in his 

 lengthy study of the benzoate question.' 



Very weak concentrations of either ben- 

 zoate or benzoic acid have no influence on 

 the rennin coagulation of milk, but with 

 an increase in the concentration there is a 

 gradual inhibition. Our results in this 



'Jmir. Frank. Inst., 147: 1899, p. 97. 

 •Wiesbaden, 1909. 



