The
reaction between an
antibody and an
antigen during an
immunology lab procedure where the two are allowed to
diffuse toward each other through an
agar-
gel medium. Lines of
precipitation form in the places on the gel where the two
react with each other and shows where the reaction has occurred.
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.