INVESTIGATIONS IN HUMAN NUTRITION. 393 



accepted standards. In his later volume the author upholds the 

 position advanced in his earlier writings that the protein intake 

 may be materially less than the usual dietary standard requires, and 

 in his discussion of the question quotes the results of a number of 

 experiments with dogs on what he considers a low proteid diet in 

 which the subjects maintained nitrof^en equilibrium and body 

 weight, or in some cases made slight gains. The author has incor- 

 porated in this volume the results of obseixations and experiments 

 carried on during recent years, by himself and his associates, and 

 discussed and summarized this work and other data with special 

 reference to theories of nutrition. The subjects treated include 

 foods and their digestion, absorption, assimilation, and the processes 

 of metabolism, the balance of nutrition, the source of energy, of 

 muscular work, with some theories of proteid metabolism, dietary 

 habits, and true food requirements, as well as additional experiments 

 and observations bearing on the subject of food requirements, and 

 the effects of a low proteid diet on high proteid animals. Sugges- 

 tions for the application of the author's theories and deductions 

 are presented. 



Extending the work carried on by Chittenden, Fisher " has made 

 studies of low proteid rations with Yale students from which he has 

 drawn similar deductions and interesting sociological conclusions. 



F. G. Benedict ^ has also discussed the nutritive requirements of 

 the body. Basing his deductions on the results obtained by the 

 respiration calorimeter, he points out that the energy intake can be 

 diminished safely only as the energy output, or the muscular activity, 

 is lowered. He further cites facts from animal physiology and dietary 

 conditions among different races of the world as indications that the 

 protein standards can not with safety be greatly lowered. 



S. C. Meltzer*^ has made another interesting and valuable contribu- 

 tion to this question. Starting with a comparison drawni from 

 engineering that structuies and machines are built to possess a 

 strength or capacity beyond the usual demand upon them, he shows 

 how — 



all orpans of the body are built on the plan of superabundance of structures and energy, 

 (and denies that the single instance of food roquirenientt*] the minimum is meant by 

 nature to be the optimum, [but maintains that] with regard to the function of supply 

 of tissue and energy by means of proteid food, nature meant it should be governed by 

 the same principle of aflluence which governs the entire construction of the animal 

 for the safety of its life and the perpetuation of its species. 



a Lake Placid Tonf. Home Econ. Proc, 8 (190G), p. 76; Science, n. ser. 24 (1906), 

 No. 620, p. 631; Yale Med. J.iur., 1907, March; Trans. Conn. -Vcad. Arts and Sci., 13 

 (1907), p. 1. 



^Amer. Jour. Physiol., 16 (1906), No. 4, p. 409; T.ake Placid ("i.iif. Home Econ. 

 Proc., 8 (1906), p. 64. 



cJour. Amer. Med. Assoc., 48 (1907), No. 8, p. OOo; Science, n. ser. 25 (1907), No. 

 639, p. 481. 



