This paper presents an analysis of agricultural extension services according to three models or images borrowed from communication sciences. The first refers to a mechanical perspective, typical of the transmission of knowledge, as a telegraph. The second, the psychosociological type, proper to the interpersonnal communication pictures extension as an orchestra where the finality is not to transmit but to play together, in harmony. Finally we propose an examination of agricultural extension based on an image proper to organizationnal commu- nication,"la poupée russe", which suggests that agricultural extension is a process of construction of the relationship between the advisor and the farmer, the rapport between them and their organisations as much as the object and the process of knowledge .
