LettersDiscussion and Correspondence THE HUMAN YOLK SAC By Leslie B. Arey See allHide authors and affiliations Science 21 Jul 1922:Vol. 56, Issue 1438, pp. 77-79DOI: 10.1126/science.56.1438.77 Leslie B. AreyFind 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 above.