Fig. 7. Graph summarizing the results of pre-incubation experiments for Drosophila tubules. All amino acids were used at 20 mmol l^-1 except for threonine (10 mmol l^-1) and tyrosine (0.5 mmol l^-1). Each bar represents the mean secretion rate (+ S.E.M.) as a percentage of the corresponding control mean. The broken line indicates the control rate (100%). N=8-16 tubules for each amino acid and corresponding control group. Asterisks represent significant (P<0.05) increases or decreases in secretion rate relative to controls.