Letter from Howard Walter Florey to Erik Jorpes, Kemiska Institution, Karolinska Institutet, Stockholm Thanks for letter and for supply of standard - says his interest in secretin is connected with its possible action on Brunner's glands - comments on this - says Heatley is having difficulty with assay because of inferior rates - comments on this - is sending manuscript of Love's paper on secretin assay in the rat - pure secretin will have very high activity - comments on difficulty in getting raw material - suggests further, closer collaboration. 1 February 1957