A device comprising a rotating means enclosed in a housing and having a horizontally arranged rotating shaft. Containers for cassettes containing samples are mounted on the rotating shaft and are joined in the form of a vertically arranged ring. The device has a means for rotating the rotating shaft at a variable speed and vessels containing processing and infiltrating liquids, said vessels being arranged outside the housing and being connected thereto by pipes for feeding in and discharging said liquids. The device additionally contains a mechanism for orienting the containers for cassettes containing samples, which mechanism is arranged between the ring of containers and the wall of the device, has a separate means for transferring the containers for cassettes containing samples into a horizontal or inclined position and holds same in the horizontal or inclined position.

A mixing device includes a mixing container for receiving mixing material and a mixer cover, wherein a first seal and a second seal is provided between the mixing container and the mixer cover. The first seal and the second seal are so arranged that a first air space is formed between the first seal and the second seal.