Abstract: A device automatically applies an object (7) to a cutting edge (11) of a knife 10), and automatically makes an initial cut in the object (7), in microtomes, especially ultramicrotomes. Force sensors (27,28), length sensors (29) or other sensors, an elecrotronic control unit (25) and an encoder (22) coupled to a drive device register forces (k,-k) connected with the separation of sections by the knife edge (11) or variations in the system triggered by these forces. Subsequently, via the electronic control unit (25), a transition from a rapid speed or rate of feed to a lower cutting speed or a lesser rate of feed for making an initial cut is automatically performed. A visual and/or acoustic signal informs the user of this change. Signals (S.sub.1, S.sub.2) from the sensors (27-29) serve for automatic adjustment of the position of two switch-over points (U.sub.1, U.sub.2) from the rapid return speed (V.sub.R) to the slower cutting movement (V.sub.

Abstract: A device for controlling the drive and forward feed of a microtome, particularly an ultramicrotome, includes a driving motor for moving a specimen or knife and a servomotor for generating a forward feed of the specimen towards an edge of the knife or vice versa. A high travelling speed of the specimen needed for rapid initial cutting is coupled to a high rate of forward feed. One single switching operation is performed, for instance, by a snap-engaging step switch via relay switches. The driving motor and the servomotor can be simultaneously switched over to pairs of values which correspond to subsequent rough cutting and ultra-thin cutting. Individual values for cutting speed and forward feed are separately preselected, readjusted, and read from a display. Selected program stages are indicated by signals.

Abstract: A refrigerated chamber includes, inside a metal wall and a foam insulating layer thereof, a sheet metal tank, in which, depending on levels of filling with liquid nitrogen, various compartments of the tank divided by separations, of different height are filled with LN.sub.2. Thereby, different cooling powers are available for varying temperature ranges between ambient temperature and the temperature of the liquid nitrogen. In this way one avoids an excessive consumption of nitrogen. Filling with LN.sub.2 is effected from a separating tank by means of a horizontal small-diameter pipe which during operation of the chamber is always exposed to and cooled by liquid nitrogen. Nitrogen in the form of a sweeping gas emerges in a boiling state from the tank and is guided through a cutting space (41') and can be heated by a heating plate fixed to sheet metal deflectors.

Abstract: A method for metal-mirror cryofixation of bio-medical or similar technical specimens in which a specimen is brought into contact with a highly polished, cooled metal mirror in order to cool at least a marginal zone of the specimen suddenly to a low temperature. In order to avoid deformation of the specimen caused by freezing, provision is made, immediately after the first contact between the specimen and the metal mirror, to press the latter against one another by an additional independent force until the specimen is completely frozen. A cryofixation device for this purpose comprises a force generating device, for example, a separate power storage device (135) which, under control, functions after contact between the specimen (106) and metal mirror (102), in other words exerts the additional force between the specimen and the metal mirror (FIG. 7).

Abstract: A specimen working chamber having heat-conductive walls instead of insulative walls is disclosed.