The NCI continued to commission work to collect more "Taxus" bark and to isolate increasing quantities of taxol. By 1969, of crude extract had been isolated from almost of bark, although this ultimately yielded only of pure material, but for several years, no use was made of the compound by the NCI. In 1975, it was shown to be active in another "in vitro" system; two years later, a new department head reviewed the data and finally recommended taxol be moved on to the next stage in the discovery process. This required increasing quantities of purified taxol, up to , and in 1977 a further request for of bark was made.