“In the 1850s and 18605 the modern commodity dealer who purchased directly from the farmer and sold directly to the processor took over the marketing and distribution of agricultural products. In the same years the full-line, full-service wholesaler began to market most standardized consumer goods. Then in the 1 870s and 188os the modern mass retailer — the department store, the mail-order house, and the chain store — started to make inroads on the wholesaler's markets.”