Figure 1. A horizontal agarose gel apparatus. Wells are formed in the gel by placing a comb in the melted agarose before it hardens. The gel is then placed in a horizontal electrophoresis chamber filled with electrophoresis buffer and connected to a power supply. When voltage is applied to the system, the DNA migrates towards the anode in a tight ‘lane’ as shown in the diagram of the resulting gel.
Figure 2. The Southern transfer apparatus. As the buffer travels up the filter paper wick through the layers of filter paper, gel, membrane and paper towels, the DNA is deposited from the gel to the membrane. The weight (say, a textbook) ensures that all of the layers remain in close contact during the transfer process.