Tax treatment of rubber produce: part treated as taxable business income while remainder treated as agricultural income. Rule 7A treats receipts from specified rubber plant products-centrifuged latex, cenex, latex-based and brown crepes, technically specified block rubbers from field latex, and coagulum-as income from normal business. It apportions such income between an amount deemed taxable as business income and the remainder treated as agricultural income, creating a mixed character for these receipts.