Letters Letter to the Editor See allHide authors and affiliations Science 15 Mar 1963:Vol. 139, Issue 3559, pp. 1101DOI: 10.1126/science.139.3559.1101 Robert SohngenFind this author on Google Scholar Find this author on PubMed Search for this author on this site Article Info & Metrics eLetters PDF This is a PDF-only article. The first page of the PDF of this article appears below.