*To Dr. Black, the use of embryonic cells ''fundamentally constitutes the gold standard'' in medical research because of their purity and versatility. But he cautioned: ''This is a very young field. Our areas of ignorance are far greater than our areas of knowledge.'' [http://query.nytimes.com/gst/fullpage.html?res=9500E3DD1739F93BA25752C0A9629C8B63&sec=&spon=&pagewanted=print] | *To Dr. Black, the use of embryonic cells ''fundamentally constitutes the gold standard'' in medical research because of their purity and versatility. But he cautioned: ''This is a very young field. Our areas of ignorance are far greater than our areas of knowledge.'' [http://query.nytimes.com/gst/fullpage.html?res=9500E3DD1739F93BA25752C0A9629C8B63&sec=&spon=&pagewanted=print] |