1917] FOODS — HUMAN NUTRITION. 661 



feterita, dwarf milo maize, and kaoliang, obtained by feeding these to seven 

 normal young men. The grains were ground to a meal and eaten either in 

 the form of bread, with a basal ration of potato, apple sauce, butter, and sugar, 

 or as a mush, with a basal ration of apple sauce, butter, sugar, and sirup. For 

 comparison similar experiments were made with breads prepared from com 

 and wheat meals. The results of these experiments may be siunmarlzed 

 briefly as follows : 



When the liafir corn was eaten in the form of hard bread, 58 per cent of its 

 protein was digested. This value may be high owing to the large proportion 

 of milk protein in the diet. When eaten in the form of a softer bread the 

 average digestibility of the protein of the dwarf kafir corn was 51 per cent, 

 of the feterita 51 per cent, of the dwarf milo maize 40 per cent, and of the 

 kaoliang 20 per cent. When eaten as a mush the percentage digestibility of the 

 protein of the dwarf kafir corn was 48 per cent, of the feterita 48 per cent, 

 of the dwarf milo maize 34 per cent, and of the kaoliang 4 per cent. No at- 

 tempt was made to estimate the digestibility of the fat as supplied by cereals 

 since it was present in very small quantity. 



The carbohydrates of the experimental ration and of the sorghums alone were 

 found to be very completely utilized. 



" Considering the grain only, as distinguished from the ration as a whole, 

 the average value for the kafir corn (hard) bread was 98 per cent, for softer 

 dwarf kafir corn bread 96 per cent, and for dwarf kafir corn mush 96 per cent. 

 In the case of carbohydrates supplied by feterita, the average values were 97 

 per cent for the bread and 99 per cent for the mush ; with dwarf milo maize 

 96 per cent for the bread and 98 per cent for the mush ; and for kaoliang 96 

 per cent for both bread and mush." 



The corn and wheat proteins were found to be somewhat less thoroughly 

 digested than is usually the case, this being due probably to the coarseness 

 of the meals used. The average digestibility of the corn bread protein was 60 

 per cent and of the coarse wheat bread protein 77 per cent. As the experi- 

 ments with all the grains were conducted under uniform conditions it is 

 concluded that the protein of the grain sorghums is less digestible than that 

 contained in either corn or wheat. 



These experiments and information available regarding the preparation of 

 the sorghums for the table indicate that these grains are valuable as human 

 food. In cooking, care must be taken that they absorb a sufficient quantity 

 of water so that the particles of meal which are characteristically hard may be 

 well softened. The flavor of the grain sorghums is generally agreeable. 

 Although their protein is less completely assimilated than that of com or 

 wheat, they are, with the exception of kaoliang, fairly good sources of this 

 food constituent. In addition, they are a good source of carbohydrate, which 

 they furnish in a form very completely available to the body. 



On the digestibility of bread. — II, Salivary digestion of erythrodextrin in 

 vitro, J. C. Blake {Jour. Amer. Chem. Soc, 39 {1911), No. 2, pp. 315-320, figs. 

 2). — Further data are reported upon one phase of the experiments reported in 

 the first article of this series (E. S. R., 35, p. 468), namely, the effect of 

 moderate variations in concentration upon the activity of the amylases studied. 

 The following conclusions are drawn : 



" The digestion of erythrodextrin by ptyalin is a monomolecular reaction. 

 The optimum temperature for this digestion is 51° C. (91.8° F.). The tem- 

 perature coefficient is relatively small at the ordinary temperature, being 

 about the same as that of chemical reactions in general. The enzym is de- 

 stroyed at 65°. The digestion becomes disproportionately slow when the ratio 

 of substrate to enzym becomes very large. This ratio is constant for different 



