96 



SCIENCE 



[N. S. Vol. XL VI. No. 1178 



in small amounts, but when these salts were pres- 

 ent in greater concentration an activating action 

 was obtained. This action was found when highly 

 purified Lintner soluble starch and thrice repuri- 

 fied bromides were used. 



Availaiility of the energy of food for growth: 

 C; Robert Moulton, Missouri Agricultural Experi- 

 ment Station. Three beef steers were subjected to 

 digestion trials and maintenance trials. One was 

 slaughtered as a check. The other two were fat- 

 tened, one to full prime condition and the other to 

 forty or fifty days under prime. All were analyzed. 

 From the analysis the composition of the animals 

 was determined and the composition of the gain. 

 From the feed records and analyses the nutrients 

 consumed above maintenance were determined. 

 The energy equivalent of the flesh gained and of 

 the feed consumed above maintenance was calcu- 

 lated. The two fattened steers saved in flesh 

 gained 53.39 and 52.49 per cent, of the metabo- 

 lizable energy consumed above maintenance. For 

 similar conditions and a similar ration Armsby 

 shows about 55 per cent, availability. This is an 

 experimental verification of his calorimetric work. 



Investigation of the Kjeldahl method for de- 

 termining nitrogen; the influence of reagents and 

 apparatus on accuracy: I. K. Phelps and H. W. 

 Datjdt. As a result of many experiments the con- 

 clusion was reached that in all routine work in- 

 volving determinations by the Kjeldahl method it 

 is necessary to deduct from the result obtained 

 the amount corresponding to the nitrogen con- 

 tributed by reagents and apparatus in use in the 

 particular experiments. It is obvious that under 

 less carefully controlled conditions in routine work 

 the errors, which are here called inappreciable, wiU 

 become large enough to seriously effect the accu- 

 racy of the results obtained. 



A study of the estimation of fat in condensed 

 milk and milk powder: C. H. Biesterfeld and O. L. 

 EvENSON. The Roese-Gottlieb method as applied 

 to condensed milk and milk powder gives low re- 

 sults, the average error in the case of condensed 

 milk being 0.04 per cent. The residual fat is ob- 

 tained by treating the liquid left after three ex- 

 tractions by the Eoese-Gottlieb procedure with 

 acetic acid, heating and reextraeting with ethyl 

 and petroleum ethers. A method also is described 

 which permits the recovery and repeated use of the 

 solvents. 



The Schneyer method for the determination of 

 lactic acid in urine: Makt E. Maver. The 

 Schneyer method for the quantitative determina- 

 tion of lactic acid in urine is not applicable, par- 



ticularly under pathological conditions. The 

 method is based on the production of CO when the 

 ether extract of urine is treated with H^SO,. 

 Hippuric acid is present in the ether extract and 

 does yield - CO. Other substances yielding CO, 

 such as oxalic and citric acid, do not enter the 

 ether extract by this method. Citric acid is pres- 

 ent in normal urine. The method is of unques- 

 tionable value in indicating the excretion of sub- 

 stances under pathological conditions which belong 

 to a group of substances capable of yielding CO 

 under the conditions of the experiment. 



On the optimum reaction for tryptic proteolysis : 

 J. H. Long and Maky Hull. It has generally 

 been assumed that tryptic digestion is possible in 

 a neutral or slightly alkaline medium only, but 

 some recent investigations suggest that these lim- 

 its are too narrow. Employing fibrin as a sub- 

 strate, the authors have found the optimum point 

 at a hydrogen ion concentration between lO-s and 

 5 X 10-9, which is in agreement with the results of 

 Michaelis and Davidsohn for a fibrin peptone sub- 

 strate. The authors have found, however, that for 

 casein as a substrate the optimum point is dis- 

 tinctly higher, and within the limits 3 X lO-e and 

 5 X lO-'. It is probable that for each type of 

 protein there is a distinct range for the optimum 

 activity and that casein may not be the only pro- 

 tein which is changed readily on the acid side of 

 neutrality. Investigations on other proteins are 

 in progress. 



On the normal reaction of the intestinal tract: 

 J. H. Long and Frederick Fenges. Employing 

 the electrometrie method of estimation the au- 

 thors have studied the reaction of the small intes- 

 tines of a number of animals and also of man. 

 Misled by the false interpretation of the resiilts of 

 indicator tests certain writers have reached wrong 

 conclusions regarding the normal or usual reac- 

 tion between the pylorus and the lower end of the 

 ileum. In the case of animals the whole intestine 

 has been removed immediately after death, tied 

 into three loops and each loop investigated sepa- 

 rately. In some cases the reaction has been found 

 to be acid throughout and from 1 to 3 X 10-". 

 Alkaline reaction seems to be less common than 

 acid, and far from the strength once assumed for 

 the duodenum with its alkaline ' ' zone. ' ' In the 

 human subject material has been secured from 

 points well below the duodenum by aid of Eehfuss 

 tubes. An acid reaction is frequently noted here 

 and persisting more frequently than the tempo- 

 rary alkalinity following the entrance of bile and 

 the pancreatic fluids 



