Learning( 2) Primary Response Secondary Response Cross-Reactive 1+Re30 Lag Lac Response Response to ag to Agr Re esponse to AgI Response to Time Antigen Agr Antigens Antigen Agl, Ag Ag1 AgLearning (2) Antigen Ag1 Antigens Ag1, Ag2 Primary Response Secondary Response Lag Response to Ag1 Antibody Concentration Time Lag Response to Ag2 Response to Ag1 ... ... Cross-Reactive Response ... ... Antigen Ag1 + Ag3 Response to Ag1 + Ag3 Lag