Facts: Three types of grain trading:
(1) spot sales: sales of grain already available for immediate delivery;
(2) Future sales: agmt for future delivery;
(3) Sales to arrive: agmt to delivery grains already in transit to Chicago. Restraint in case dealt with sales to arrive & sold at a special session called “A Call” i.e., the Call rule. It was an open bid market where the price of grain is displayed.