 As suggested in the brief history above, experimentation figured prominently in the rise of molecular biology (see the entry on  experiment in biology).  X-ray crystallography allowed molecular biologists to investigate the structure of macromolecules.  Alfred Hershey and Martha Chase (1952) used phage viruses to confirm that the genetic material transmitted from generation to generation was DNA and not proteins (see Hershey-Chase Experiment in  Other Internet Resources).  Muller (1927) used x-rays to intervene on and alter gene function, thus revealing the application of methods from physics to a biological domain (see Elof Carlson on Muller’s Research in  Other Internet Resources).  