The Short Version
Bacterially produced double-stranded RNA is ingested by Caenorhabditis elegans and triggers target-specific gene knockdown through the worm’s own RNAi machinery. Primary feeding experiments and uptake studies support this mechanism. The wording “endogenous RNA interference pathway” is technically loose: ingested dsRNA triggers exogenous RNAi, which shares components with distinct endogenous RNAi pathways.