The Story of M
  The origins of the 11-dimensional supermembrane are recalled, and a curious property is discussed: the field theory limit of a supermembrane in a hyper-K\"ahler background is a 3-dimensional sigma-model with N=4 supersymmetry, but the higher-order fermion interactions of the supermembrane generically break this to N=3. 
Paul K. Townsend