A person who is not one of the mutual agents of the firm and has not controlled, determined, fixed or limited the agency through which the business is conducted, and has no power to do so, is not a member of the firm. For it is a necessary element of a partnership that the business be conducted through an agency which the members have created. The converse of the proposition, however, is not true. A person may put money into a business by way of loan, and share in its profits as a return for such use, and besides stipulate for his own safety and security that a certain person [or persons only shall manage the business, and do this without becoming a member of the partnership. But the stipulation must be simply in the nature of a guaranty for security as shown by all the terms of the contract and the situation of the parties. Any right reserved to direct or control the agency might be fatal to non-responsibility. The stipulation in effect would amount only to this: On condition of certain persons being in control of the business, a certain amount of money is loaned to the firm for a certain limited time and for a certain consideration not amounting to any permanent interest in the firm.