[Supplementary report on the study of resistance to coumafene in Rattus ratus observed at Marseilles]

A resistance to coumafene has previously been observed among Rattus rattus in a foodstuffs warehouse in the port of Marseille. New tests are here reported. They concern rats captured in two warehouses situated at a distance of 1,000 m. from one another, and separated by a distance approximately similar to that of the first warehouse explored. The experiments which were carried out, although limited in number, have clearly shown a resistance to coumafene administered in high doses in a rat of the first group and in three rats of the second group. There is every reason to fear a resistance extended to all the territories where Rattus rattus are found in the harbour and in the neighbouring regions.