Abstract: A development tank for the daylight development of photographic material comprises inner and outer vessels, axially reciprocal in relation to one another, and defining between them an annular space in which the material to be treated is placed in the absence of light, this space then being closed light-tight by a lid. The inner vessel provides a water bath by which the treatment solution is heated and maintained at the desired temperature. The treatment solution is introduced into a closable conduit and is delivered to the annular space and discharged therefrom by the axial movement of the vessels relative to one another.