Letter from Thomas Gold to Dr Richard S Hanson, Department of Bacterialogy, University of Wisconsin, Madison, Wisconsin Gold is enclosing a letter to Dr Nierenberg and a reply by Dr Nealson that will describe the nature of his enquiry. Gold would be most grateful for any information he can give on this topic. It seems to Gold from a study of the relationships in many hydrocarbon deposits, that such a process would provide a much better explanation there than the conventional one. If there is a serious possibility of this, it could become a matter of considerable practical importance. 3 May 1979