Abstract: An annunciator and/or shut-down system for an automatic processor for treating tissue specimens. In a tissue processor of the type wherein the reagents are drawn from reagent containers into the reaction vessel by drawing a vacuum on the vessel and reagents are returned to their respective reagent containers by gravity, the filled or unfilled condition of the reaction vessel is determined by sensing the vacuum condition during two time intervals; one near the start of filling and one just after filling is normally completed. The vacuum condition indicative of a filling or filled vessel differs for each sensing time interval. Logic circuitry analyzes the sensor condition for the specific time interval and, if the condition is maintained over a predefined delay period, outputs a short duration shut-down signal which causes latching of a mechanical shut-down and/or annunciator switch.

Abstract: This invention relates to apparatus for processing histological tissue specimens and the method of processing the specimens utilizing the apparatus. More particularly, the apparatus provides means for automatically processing the specimens in a single container by sequentially introducing and removing solvents and/or paraffin into and from said container.

Abstract: The dispensing apparatus includes a syringe having a plunger therein and appropriate inlet and discharge openings associated therewith. Two cams are positioned in spaced relationship with a connecting rod mounted to an eccentric of each cam and pivotally to the plunger in the syringe. Motor elements cause rotation of one of the cams with the second cam acting as the fixed pivot point to move the plunger through a first distance. Rotation of the second cam with the first cam acting as the fixed pivot point causes the plunger to move through a second distance. Two liquid volumes are, therefore, dispensed from a single syringe in which one-half cycle of rotation of either cam acts to fill the syringe and the other half cycle acts to discharge the syringe. A multistation dispenser is provided by using a plurality of syringes and connecting two such cam assemblies to a cross bar which causes simultaneous reciprocation of the various plungers associated with the plurality of syringes.