FOODS HUMAN NUTRITION. 167 



although carhonic-acid gas is antiseptic and germicidal to a considerable extent, 

 it can not be relied upon as a sanitary safeguard since it does not inhibit or Ivill 

 all micro-organisms. 



Data regarding the chemical examination of a number of samples are given in 

 tabular form. An examination of 25 samples of so-called " pops " containing 

 caffein showed the average amount to be 0.8 grain per bottle of 200 cc. 



The bulletin also contains a report on the value of Endo medium as a pre- 

 sumptive test for bacteria of the Bacillus coli group. The conclusion is drawn 

 that this medium is a very reliable presumptive tost for these organisms. 



A study of the gelatinizing agents, pasty materials, and thickeners used 

 in food products, L. A. Congdon (Trans. Kans. Acad. ScL, 27 (1914), PP- Sl- 

 S6). — These substances are considered with reference to their physical and 

 chemical properties and their detection in food materials. Those most com- 

 monly used are said to be gelatin, starch, agar-agar, gum tragacanth, dextrin, 

 gum arable, albumin, and fruit and vegetable pectins. A table is given in which 

 these substances are classified into six groups, with the group reactions for their 

 detection. 



[Food and clothing in the United States Navy], S. McGowan (U. S. Navy 

 Dept, Ann. Rpt. Paymaster Gen., 1915, pp. 5-1). — Included in this publication 

 is some information regarding the purchase of food supplies, the satisfactory 

 character of the ration, and costs. It appears that for the year 1915 the average 

 daily cost of subsistence per man was 36.038 cts., as compared with 36.648 cts. 

 for 1914. The report also contains some information regarding the United 

 States Navy clothing problem, including the manufacture of garments at the 

 Charleston Navy Yard and elsewhere. 



[Progress in] physiological chemistry, F. G. Hopkins (Ann. Rpts. Prog. 

 Chein. [Loudon], 11 (191Jf), pp. 188-212). — This report contains a summary and 

 digest of the more important experimental data contributed to the science of 

 physiological chemistry during the year 1914. Among the subjects in which 

 progress has been reported are catalysis, the specificity of tissue enzyms, defen- 

 sive ferments, the metabolism of carbohydrates and fats, the creatin problem, 

 and vitamins. 



Differences in the digestion in adults and infants, J. F. McClendon (Jour. 

 Amer. Med. Assoc, 65 (1915), No. 1, pp. 12-14). — As a contribution to the 

 knowledge of the conditions under which the digestive enzyms act in the case 

 of both adults and infants, the acidity of the stomach and reaction of the duo- 

 denal contents were measured by means of hydrogen electrodes. 



After a normal meal, the acidity of the adult stomach was found to reach 

 its maximum in from two to three hours. The rise in acidity was the more 

 rapid the lighter the meal, though the degree of acidity varied with the indi- 

 vidual. The duodenal contents proved to be barely alkaline. 



As to digestion in infants, the author concludes that " the acidity of the 

 infant's stomach rises slowly after the milk begins to leave it, and four hours 

 after nursing may be the same as some normal adult stomachs. That of the 

 gastric juice of the new-born is 0.00.5. 



"The acidity of the duodenal contents of the infant is 0.0008, and hence it is 

 probable that both peptic and tryptic digestion take place in the intestine of the 

 infant. Pepsin was always found and was apparently more abundant (active) 

 than the trypsin." 



The acidity of the infant stomach, R. Hess (Ztsclir. KiJiderheilk., 12 (1915), 

 No. 6, Orig., pp. J,09-.',39 ; abs. in Zentbl. Physiol., 30 (1915), No. 7, pp. 308, 309). — 

 Examination of the stomach contents of more than 70 infants showed that in the 

 majority of cases too little acid was present during the earlier weeks to permit 



