Letters Science at Cornell See allHide authors and affiliations Science 16 Apr 1886:Vol. ns-7, Issue 167, pp. 352DOI: 10.1126/science.ns-7.167.352 H. N.Find 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.