A researcher has several different strains of T4 phage with single mutations in the same gene. In these strains, the mutations render the phage temperature-sensitive. This means that temperature-sensitive phages can propagate when the bacterium (E. coli) is grown at 32°C but cannot propagate themselves when E. coli is grown at 37°C. Think about Benzer's strategy for intragenic mapping and propose an experimental strategy to map the temperature-sensitive mutations.