Figure 1. Template for Ouchterlony immunodiffusion. Holes should be equidistant, 4 mm in diameter, with sharply cut edges.

Figure 2. (a) Reaction of identity: The lines of precipitation fuse to give a continuous arc, indicating that the two neighbouring antigens are identical in terms of what the antibody recognizes. (b) Reaction of nonidentity: The lines of precipitation cross each other, indicating that the two neighbouring antigens do not contain any common epitopes. (c) Reaction of partial identity: The lines of precipitation are partially fused but also cross over, indicating that the two neighbouring antigens contain common epitopes but are not identical. (d) More than one line indicates the antigen contains a mixture of molecules reacting with the antiserum.