A FEW WORDS ABOUT EATABLES. 681 



a long time unless lie also do a large amount of muscular work unless 

 he do much more work of this sort than the great majority of human 

 beings are willing or able to do. Fat and butter and oily matter gen- 

 erally, on the other hand, require no digestion, in the proper sense of 

 the word. They are converted into an emulsion which is no more 

 than a mechanical mixture like cream, by the action of the pancreatic 

 and duodenal juices chiefly, and by the action of the bile partly, and 

 this emulsion passes directly into the general circulation of the blood 

 through the lacteals directly, without going the round of the portal 

 circulation and the liver, as albuminose has to do. Fat and butter 

 and oily matters generally are fuel ready-made, or which only need to 

 be emulsified in order to be in this case ; and they have this advan- 

 tage also that they are burned up in the system, without leaving be- 

 hind them, so to speak, any ash like urea. And, as force-producing 

 agents if the capacity for oxidization may be taken as a measure 

 the value of fat and oil is almost double that of fibrine or albumen. 



C. I can see that I may have been taking too much lean meat and 

 too little toast ; I can also see that I may have been especially wrong 

 in avoiding fat and butter ; but I do not see how to set to work to 

 reform mv doings. 



31. What you have to do, first of all, is to bear in mind that the 

 daily loss which has to be made good by food, in a man of medium 

 stature and in moderate work, amounts to 4,800 grains of carbon and 

 300 grains of nitrogen, and that, in round numbers, lean meat contains 

 11 per cent of carbon and 3 per cent of nitrogen, and bread 30 per 

 cent of carbon and 1 per cent of nitrogen. 



C. Is it so ? 



31. Yes. The daily rate of wasting of the system which I have 

 mentioned is that which is brought to light by very many observa- 

 tions, carried on by many persons in various ways, with a view to reg- 

 ulate the food-rations of soldiers and sailors and pi'isoners, and other 

 ration-fed people ; and as to the proportion of carbon and nitrogen in 

 lean meat and in bread the evidence is sufficiently conclusive. 



C. Upon these data I can easily calculate how much meat and 

 bread I really want if I choose to live wholly on meat or bread, and 

 how the meat and bread ought to be apportioned if I take meat and 

 bread together. 



31. The calculation is ready made for you, and the result shows 

 very plainly that you must mix your lean meat and bread in certain 

 proportions if you care to feed without wasting good food. In order 

 to replace the daily loss of 4,800 grains of carbon by lean meat, the 

 quantity of meat you must take is 43,637 grains, or rather over 6 

 pounds a quantity which contains 1,009 grains of nitrogen in excess 

 of the 300 grains actually wanted. In order to replace the daily loss 

 of 300 grains of nitrogen by bread, the quantity of bread you must 

 take will be 30,000 grains, or about 4 pounds a quantity which ex- 



