A manual injector for cell manipulation comprising a displacement device for displacing a fluid, an injection tube connected to the displacement device, and a capillary holder connected to the injection tube for holding a microcapillary tube or a microcapillary tube connected to the injection tube, wherein the displacement device has the following: a disk-shaped main body that, on a first end face, has an hollow cylinder space which is concentric with its middle axis, a disk-shaped adjusting wheel, a helical gear, a hollow cylindrical plunger, a rotational decoupling that connects the adjusting wheel to the plunger, and a connection connected to the cylinder space to which the injection tube is connected.