546 



A MANUAL OF PHYSIOLOGY 



80 grammes fat give about 60 grammes carbon, so that from 

 proteins and fat we have now got no grammes of the necessary 

 250, leaving 140 grammes carbon to be taken in about 310 

 grammes starch, or an equivalent amount of cane-sugar or 

 dextrose. Adding 30 grammes inorganic salts, we can put down 

 as the solid portion of a normal diet sufficient from the physio- 

 logical point of view for a man of 70 kilos : 



95 grammes proteins 

 80 fat 

 310 carbo-hydrates 



30 salts. 



7 J-jj of body- weight. 



!>0(T " 



525 



solid food 



Now, knowing the composition of the various food-stuffs, we 

 can easily construct a diet containing the proper quantities 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 15 grammes nitrogen or 

 95 grammes protein, he must consume more than 1,500 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 nearly 4 kilos of potatoes to obtain his 15 grammes 



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

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



