METABOLISM, NUTRITION, AND DIET. 441 



stances, or to others no less effectual, which prevented the loss of heat 

 and moisture. Cases in which life has continued after total abstinence 

 from food and drink for many weeks, or months, exist only in the imag- 

 ination of the vulgar. 



(3.) During the starvation period the excreta diminish. The urea, 

 as representing the nitrogen, falls quickly in amount, reaches a mini- 

 mum and remains constant at this point for several days, and then rises 

 again and finally falls rapidly immediately before death; the sulphates 

 and phosphates undergo much the same form of reduction. The carbon 

 dioxide given out and the oxygen taken in diminish. The fseces dimin- 

 ish, as well as the bile. It has been concluded as highly probable that 

 the greater part of the urea represents the loss of weight of the muscles. 



The appearances presented after death from starvation are those of 

 general wasting and bloodlessness, the latter condition being least notice- 

 able in the brain. The stomach and intestines are empty and contracted, 

 and the walls of the latter appear remarkably thinned and almost trans- 

 parent. The various secretions are scanty or absent, with the exception 

 of the bile, which, not being discharged, usually fills the gall-bladder. 

 All parts of the body readily decompose. 



In starvation, then, we see that the only income consists of the in- 

 spired oxygen. The whole of the energy of the body given out in the 

 direction of heat and mechanical labor is obtained at the expense of the 

 using up of its own tissues, there being as a result a constant drain of 

 the nitrogen and carbon, not to mention the other elements of which 

 they are made up. It is obvious that such a condition cannot be en- 

 dured for any length of time. 



Requisites of a Normal Diet. 



It will have been understood that it is necessary that a normal diet 

 should be be made up of various articles, that they should be well cooked, 

 and that they should contain about the same amount of carbon and ni- 

 trogen as are got rid of by the excreta. No doubt these desiderata may 

 be satisfied in many ways, and it would be unreasonable to expect the 

 diet of every aclult to be unvarying. The age, sex, strength, and cir- 

 cumstances of each individual must ultimately determine what he takes 

 as food. A dinner of bread and cheese with an onion contains all the 

 requisites for a meal, but such diet would be suitable only for those pos- 

 sessing strong digestive powers. It is a well-known fact that the diet 

 of the continental nations differs from that of our own country, and 

 that of cold from that of hot climates, but the same principle underlies 

 them all, viz. , the replacement of the loss of the excreta in the most 

 convenient and economical way possible. Without going into detail in 



