I would expect the electrophoretic samples to run further and form arrow shapes which vary in length as the concentration increases. In radial immunodiffusion the antigen diffuses and gets more dilute over the entire circumference of the well so the concentration is similar for any radius of a circle all round the well. With electrophoresis all of the sample moves quickly through the liquid solvent and then runs through the gel matrix over only part of the circular well facing the anode so the immediate concentration of the antigen is very high on that side of the well and then ets lower as it migrates in one direction through the gel

Hi Kaku Michio,

this is comparing apples with pears. The conditions are too different, even though the two methods are both based on the formation of immune-precipitates. There may be some rough correlations, but nothing that would be useful.

There is difference in principle of both immunodiffusion and immunoelectrophoresis. As both are as result of antigen and antibody reaction and precipitate formation, immunodiffusion (do not require electric field application) it take a long duration and we get a almost circular symmetric faint region, while immunoeletrophoresis we get triangular faint region, suggestion of antigen antibody precipitation reaction in both.