Don Newcomb was perplexed. It had been five yearssince he had founded Interplants, Inc., a research-and-development firm that developed geneticallyengineered plants for interplanetary space flight.During that five years, he and his scientists had made dramatic advances in developing special plants that could be used for food and air-purification systems in space stations and transports. In fact, he mused, their scientific success had been far greater than he had ever expected.