An Earthworm labelled with Radioactive Tantalum

An adult Lumbricus terrestris L. (live weight 5.3 g) was labeled with 2.0 rig of radioactive tantalum wire (Ta182) in its coelom through a slit cut laterally in the second segment behind the clitellum and apparently suffered no ill effects. Three months later the Ta was found in a segment 1 in. from the anus. The worm could be detected when it was 8 in. below the surface of the soil in its vertical burrow by a mains-operated G-M monitor. (P.C.H.)