Storehouse for Human Welfare. As environmentalists and wildlife enthusiasts argue for preservation of wild species, they sometimes overlook a most compelling fact-the survival of wild species directly benefits humans. Like the Earths most precious minerals, the planetary gene pool is a valuable natural resource that is vulnerable to irreversible harm. Yet, if present trends toward extinction persist, possibly one-third and conceivably one-half the entire spectrum of species may be lost to us within another century. What does this mean? In 1960, a child suffering from leukemia had only one chance in five of