582 THE ANIMAL BODY AS A MACHINE 



the general welfare and efficiency. Physicians seek in some instances 

 to correct the former condition by the administration of thyroid 

 extract or of other preparations which are believed to stimulate metab- 

 olism. It is quite possible, however, that the effects which are desired 

 might also, in those instances in which no manifest disease of the 

 thyroid is present, be elicited by an adequate increase in the protein 

 intake of the patient. This possibility is merely mentioned in order 

 to illustrate the probable nature of the effects and utility of a protein 

 intake in excess of our minimum needs. We must recollect that it is 

 not the energy-output which suffices merely to maintain life, to gain the 

 means of living for another day, which is of genuine value in the eyes 

 of civilized mankind. The products of human effort which we prize 

 are wholly the outcome of the small surplus of energy which we col- 

 lectively generate over and above the minimum which will support life 

 and propagate the species. This small surplus, which is minute in 

 comparison with the aggregate expenditure, is the origin of all that we 

 cherish, and, even in purely economical terms, the cost of its production 

 is negligible in comparison with its value. In the absence of any 

 evidence of deleterious influence, a reasonable excess of protein -intake, 

 such as that usual in the United Kingdom or America, should not be 

 discouraged in advance of a clear demonstration that it plays no part 

 in the generation of efforts which, in the aggregate, may outweigh the 

 costliness of the practice. It must be admitted, however, that even 

 upon this basis it is difficult to defend the extraordinarily excessive 

 meat-consumption which has hitherto been customary in Australia. 



THE NORMAL DIET. 



The normal dietary of a variety of different classes and occupations 

 of society in the United States has been investigated by Atwater both 

 from the standpoint of composition and that of Calorific Value. The 

 following table summarizes some of his results. It must be recollected, 

 however, that the quantity of food actually digested, assimilated and 

 utilized, was in each instance a little less than the quantity which was 

 ingested. 



Composition of the diet. 



Calories 

 per day. 



3560 

 3605 

 3530 

 3880 

 3705 

 3405 

 8850 

 6905 

 5740 

 4462 

 2910 



3465 



