Concentrations of copper, manganese, zinc, nickel, cadmium and lead were measured in samples of liver, kidney, brain, heart, lung, skeletal muscle and vertebral bone from forty foetuses of 23-43 weeks gestation. 2. Cu concentrations in the liver were up to 100 times those in other tissues, but only those in the brain showed a significant increase with gestational age. 3. Mn concentrations were similar in all tissues; the over-all range was 0.35-9.27 microgram/g dry matter (DM). 4. Concentrations of Zn in the liver were much higher than in other tissues and decreased with gestational age, whereas levels in skeletal muscle increased. 5. In all tissues Ni concentrations were within the range 0.04-2.8 microgram/g DM and levels in kidney and muscle decreased significantly with age. 6. Cd was detected in most of the tissue samples and concentrations were within the range 0.01-0.58 microgram/g DM. 7. Concentrations of Pb, where it was detected, varied from 0.1 to 2.4 microgram/g DM in the soft tissues and from 0.4 to 4.3 microgram/g DM in the bone samples.
