Conceding, but not deciding, that the plaintiffs here have otherwise made a proper showing and pursued the proper procedure and that this is a case in which parties defendant may be added in the manner here sought, neither the original petition nor the amendment contained any allegations of fact which would render the corporation and the defendant O'Neal liable to the plaintiffs for the death of their mother. The mere fact that Williams, the corporation and O'Neal were engaged in a joint venture and that they jointly owned the automobile involved in the collision, was not sufficient to render the other joint venturers liable for the negligence of Williams. It is nowhere alleged in the petition that Williams was acting as the agent of the others or that he was about the business of the joint enterprise at the time the collision in question took place. It follows that the original petition as amended failed to state a cause of action against the corporation and against O'Neal, and the judge did not err in striking the amendment and in dismissing the action as to those defendants. Code 75-308; Rogers v. Carmichael, 184 Ga. 496 (2) (192 SE 39); Rogers v. Carmichael, 58 Ga. App. 343 (1) (198 SE 318); Bowman v. Fuller, 84 Ga. App. 421, 426 (66 SE2d 249); Mansour v. Mobley, 96 Ga. App. 812, 816 (1b) (101 SE2d 786); 30 Am. Jur. 982, Joint Adventurers, 56; 38 Am. Jur. 942, Negligence, 253, n. 12.