Earthworms were kept on a water-agar gel for 96 h at 20°C, after that time all soil had been voided from their guts. Earthworms treated in this way may be used for soil-free chemical analysis, as required in biomonitoring programmes for soil contamination. (C) 2000 Elsevier Science Ltd.
Pokarzhevskii, A. D., van Straalen, N. M., & Semenov, A. M. (2000). Agar as a medium for removing soil from earthworm guts. Soil Biology and Biochemistry, 32, 1315-1317. https://doi.org/10.1016/S0038-0717(00)00018-3