AbstractAn electrophoresis apparatus of the vertical slab gel type was designed to obtain a unit in which the number of spare parts and manual operations necessary for its assembly is significantly reduced as compared to the designs that are commonly used at present. The new apparatus is assembled in less than 60 s, and the gels are mouldedin situ.,i. e.without the use of a separate casting stand. With all electrode reservoirs placed within the base unit, the apparatus obviates the need for bulky external electrode reservoirs. The compact design is made possible by use of a permanently mounted porous plastic bridge that acts as a seal during moulding of the gel and as a conducting salt bridge during electrophoresis. The apparatus permits simultaneous running of two gels, and runs on single gels may be performed independently without filling the electrode reservoirs for the other gel.