Referee's report by Edwin Stephen Goodrich, on a paper 'Experiments on the development of chick and duck embryos, cultivated in vitro' by Conrad Hall Whaddington Sectional committee: Zoology Recommended for publication in Philosophical Transactions, in full. It is a valuable contribution as the author has overcome technical difficulties to discover important new results. He objects to the author's use of the word 'mesoderm', as its definition in embryology is quite different. The word 'ectomesoderm' should be used instead. [Published in Philosophical Transactions B, 1932]. Endorsed on verso as received 5 October 1931. October 1931