All averments of claim or defense shall be made in numbered paragraphs, the contents of each of which shall be limited, as far as practicable, to a statement of a single set of circumstances; and a paragraph may be referred to by number in all succeeding pleadings. Each claim founded upon a separate transaction, or occurrence, and each defense other than denials, shall be stated in a separate claim or defense whenever a separation facilitates the clear presentation of the matters set forth.