662 EXPEEIMENT STATION" EECOED. 



The author points out a number of errors which should be avoided in chang- 

 ing from one diet to another, and gives tveo methods of changing from a high 

 protein to a low protein diet. 



The appendix contains a discussion of the fundamental principles of foods 

 and several dietaries. 



The effect of completely hydrolyzed food on the digestive tract, O. Cohn- 

 HEiM (Eoppe-Seyler's Ztschr. Physiol. Chem., 84 {WIS), No. 7, pp. 419~Jt24).— 

 Experimental data are presented showing the effect produced upon the digestive 

 secretion by two commercial food products which it is claimed are prepared 

 by the reduction of protein food to the elementary " building stones " or amino 

 acids without any loss of the food material. 



When fed to dogs having duodenal and gastric fistulas, almost as much secre- 

 tion was observed as in the case of the ordinary imchanged food, and the food 

 passed the stomach no quicker. Solutions of these preparations injected into 

 the small intestines were completely absorbed and produced no secretion. 



The ferments of the pancreas.-^I, The generation of trypsin from ti-ypsino- 

 gen by enterokinase, J. Mellanby and V. J. Woolley {Jour. Physiol., 45 {1912), 

 No. 5, pp. S70-38S, figs. 2). — Experimental data are given, with the following 

 conclusions : 



" The length of time taken by the activation process is a function of the 

 amount of enterokinase added. After the addition of a definite amount of 

 enterokinase trypsin is produced at a constantly increasing rate as the reaction 

 proceeds. The velocity of the change is accelerated by a rise in temperature. 

 The reaction proceeds most quickly in neutral solution, is delayed by alkali, and 

 stopped by acid. There is no evidence that tiypsin can activate trypsinogen or 

 that trypsin can act as a coenzym to enterokinase. Proteins apparently delay 

 the activation process, but this observed delay is probably due to the absorp- 

 tion of the first formed trypsin by the protein, the amount of delay vaiying 

 with different proteins." 



These results are explained by the authors on the ground that enterokinase 

 is a proteolytic ferment, acting best in a neutral solution, which liberates the 

 trypsin from the trypsinogen. 



The ferments of the pancreas. — II, The action of calcium salts in the g'en- 

 eration of trypsin from trypsinogen, J. Mellanby and V. J. Woolley {Jour. 

 Physiol., 46 {1913), No. 2, pp. 159-172). — Experimental data are presented which 

 indicate that calcium salts are not essential for the action of enterokinase or 

 trypsinogen, since this action can take place in calcium-free solutions and 

 barium and strontium salts can activate pancreatic juice as effectively as those 

 of calcium. 



The activation of pancreatic juice by calcium salts is explained by the 

 authors on the ground that pancreatic juice always contains enterokinase but 

 in some instances it is present in so small an amount that its action is in- 

 hibited by the alkali of the pancreatic juice. The addition of calcium salts to 

 the juice removes the alkali and thus accelerates the rate of trypsin production. 



Comparative study of the ti^ptic digestion of raw milk and of milk dried 

 at high temperatures, E. C. Avikagnet, H. Doblencouet, and M. Bloch ( Compt. 

 Rend. Soc. Biol. [Paris], 74 {1913), No. 15, pp. S85-SS7, fig. i ) .—According to 

 the results obtained by other workers, which are referred to in this article, the 

 higher the temperature at which the milk is dried the greater is the digestibility 

 of the product obtained, provided the heat is not raised higher than 130-140° C. 

 and is applied for only a short time. Prolonged heating tends to increase the 

 digestibility. 



In the experiments described samples of raw milk and of solutions of dried 

 milk containing equal amounts of nitrogen were treated with the same quantity 



