FOODS AND NUTRITION 381 



market the crop (Figure 338). Now our transportation 

 facilities are so highly organized that it is possible to dine 

 on various perishable foods in places far removed from 

 the food sources (Figure 339). 



The study of our food supply involves a study not 

 only of food production, but a study of food preservation, 



FIG. 338. Wheat Harvesting. 

 A modern oil tractor operating five binders. 



of food conservation, of transportation, and of industrial 

 conditions. 



Food Preservation as Related to Food Supply. 

 Modern methods of preserving foods make it easy to 

 maintain a dietary in times and places of relative scarcity 

 which otherwise would be impossible. Some of the 

 methods of preserving foods have been in use for a long 

 time. These include drying, canning, salting, pickling, 

 and smoking (Figure 340). The use of low tempera- 

 tures and certain chemicals other than salt for preserving 

 foods is of comparatively recent development. Cold 

 storage methods have the great advantage of preserving 



