METABOLISM, NUTRITION AND DIETETICS 477 



Now, knowing the composition of the various food stuffs 

 we can easily construct a diet containing the proper quan- 

 tities of nitrogen and carbon, by using a table such as the 

 following : 



Economic and social influences prices and habits and not purely 

 physiological rules, fix the diet of populations. The Chinese labourer, 

 for example, lives on a diet which no physiologist would commend. 

 In order to obtain 20 grammes nitrogen or 140 grammes proteid, 

 he must consume nearly 2,000 grammes rice, which will yield 700 

 grammes carbon, or twice as much as is required ; but if the Chinese 

 labourer could not live on rice, he could not live at all. The Irish 

 peasant is even in worse case ; he must consume 5 kilos of potatoes 

 to obtain his 20 grammes nitrogen, while little more than half this 

 amount would furnish the necessary 300 grammes carbon.t A man 

 attempting to live on flesh alone would be well fed as regards 

 nitrogen with 600 grammes of meat, but nearly four times as much 

 would be required to yield 300 grammes carbon. Oatmeal and 

 wheat-flour contain nitrogen and carbon in nearly the right propor- 

 tions (i N : 15 C), oatmeal being rather the better of the two in this 

 respect ; and the best-fed labouring populations of Europe still live 

 largely on wheaten bread, while, one hundred years ago, the Scotch 

 peasant still cultivated the soil, as the Scotch Reviewer the Muses, 

 ' on a little oatmeal.' But although bread may, and does, as a rule, 

 form the great staple of diet, it is not of itself sufficient. 



* A cheese manufactured from whole milk, curdled before the cream 

 has had time to rise, and therefore rich in fat. 



f Of course a diet consisting, week in week out, entirely of potatoes or 

 rice, would represent an extreme case. A certain amount of the necessary 

 nitrogen is often obtained even by the poorest populations, in the form of 

 fish, milk, eggs or bacon. 



