of preservatives to the agarose solutions, for example 0.1% sodium azide or 0.01% sodium merthiolate. Simple equipment is commercially available, thoughmuch can be made in-house. The electrophoresis system only requires two electrophoretic tanks (provided with platinum wire and connected to the electrodes), and an adjustable power supply delivering voltage up to 400 V at 400 mA. The connection between the agarose plates and the buffer in the tanks can be accomplished through Rlter-paper wicks previously wetted in electrophoretic buffer (the same as that used for preparing the gel). To avoid excessive warming of the gel during electrophoresis, it is convenient to cool the agarose plates using a system connected to tap water. This allows the electrophoresis to be run at room temperature in the laboratory, alternatively, it can be carried out in a cold room at 53C. A great number of polyvalent and speciRc antisera prepared in goat, sheep or rabbits can be obtained from different suppliers or obtained in-house.