Letter from Howard Walter Florey to J S K Boyd, Wellcome Foundation, Euston Road, London Says that in 1956 the Foundation prmosed them acetone-dried mucosa to provide starting material for purification of secretin - has become clear that pure hormone has very high activity - large supplies of crude product will be needed to try to isolate secretin in homogeneous state - comments on Eli Lilly, who are willing to supply them with somecrude secretin - asks if Wellcome Laboratories would object to this - Lilly could only supply fraction of requirements. 17 May 1957