THE FOOD SUPPLY 497 



Now in view of our absolute dependence on solar radiation, it is a 

 rather startling fact that but the smaller part of the energy stored up 

 in the farmer's crops is directly available for man's use. Of that of the 

 wheat crop, for example, fully sixty per cent, is contained in the straw 

 and another 10 per cent, is rejected in the process of milling as bran 

 and other by-products. In other words, only about 30 per cent, of the 

 energy stored in an acre of wheat is directly available for human nu- 

 trition. Much the same thing is true of most other food crops, while 

 the grasses and clovers, so important in all systems of agriculture, are, 

 of course, entirely unavailable as food for man. Hitherto, our enormous 

 surplus of food products has served to obscure the significance of this 

 fundamental fact. Not only have we been able to export vast quanti- 

 ties of breadstuffs to less fortunate lands, but we have used other mil- 

 lions of bushels of edible products, especially corn, as food for domestic 

 animals. America has been a country of cheap animal food — meat, 

 eggs, milk, butter, cheese, etc. — and we have been fond of drawing the 

 comparison between the abundant meat supply of our working classes 

 and its comparative scarcity in the diet of the European laborer and, 

 rightly or wrongly, have attributed much of the greater industrial effi- 

 ciency of our workmen to this difference in diet. 



But we are rapidly approaching an economic limit to the production 

 of meat from edible grains. Such a conversion is an exceedingly waste- 

 ful process. Of the solar energy stored up in a bushel of corn, less than 

 3 per cent, is recovered in the edible portion of the carcass of the 

 steer to which it is fed, while even in pork production this percentage 

 scarcely rises to more than 16, and in milk production to about 18, and 

 similar losses are observed in all branches of animal production. In 

 other words, the stockman who feeds his animals on grain is expending 

 energy available for human use as fuel for his animal machines for the 

 sake of recovering a small fraction of it in higher priced and more 

 palatable products, a process which can hardly fail to remind one of the 

 reputed origin of roast pig. So long as our food supply was vastly in 

 excess of our needs, such practises were doubtless economically justifi- 

 able. To the solitary hunter in the primeval forest it was a matter of 

 comparative indifference whether he made his camp fire of underbrush 

 or of the best grade of timber, but with lumber at its present price, the 

 mill owner can afford only sawdust and refuse to feed his fires. In the 

 past, speaking broadly, our meat production has consisted to a large ex- 

 tent in the exploitation of our food resources. There has been a choice 

 between producing bread or meat, and the improvements in stock hus- 

 bandry have been largely in the direction of more profitable exploita- 

 tion. In the near future, we shall have to reverse this attitude and 

 study the conservation of the food supply. Not much longer can we 

 continue to take the children's bread and cast it to the brutes. If our 



VOL. LXXIX. — 34. 



