This is an appeal from an order of the trial court overruling appellant's plea to the jurisdiction of the trial court, the plea being asserted in a special appearance made pursuant to the right conferred by Rule 120-a, T.R.C.P. Tommy D. McCulley, Jr., individually and as next friend of Tommy D. McCulley, III, sued appellant and three other defendants, to recover damages for personal injuries suffered by Tommy, III, when a door on a school bus came open while Tommy III was a passenger, causing him to fall from the bus. Appellant was alleged to be the manufacturer of the bus. It was alleged that appellant was a foreign corporation doing business in Texas and that it had failed to appoint an agent for service. It was asked that service be made upon the Honorable Crawford D. Martin, Secretary of State, pursuant to the provisions of Article 2031b, Sec. 3, V.A.T.S. Service was so made. Appellant filed its motion that the service be held invalid and that it be quashed.