What is the test for determining proximate cause in a motor vehicle accident?

"On the question of proximate cause Binford v. Johnston, 82 Ind. 426, 42 Am. Rep. 508, is in point. * * * `It is firmly settled that the intervention of a third person or of other and new direct causes does not preclude a recovery if the injury was the natural or probable result of the original wrong. * * * The rule goes so far as to hold that the original wrong-doer is responsible, even though the agency of a second wrongdoer intervened.' * * *"