A model for asymmetric septum formation during sporulation in Bacillus subtilis. 
Many differentiation processes in both prokaryotes and eukaryotes begin with an asymmetric division, producing 'daughter' cells that differ in size and developmental fate.  This is particularly obvious in the well-studied prokaryotic life cycles of Caulobacter and Bacillus.  In no system, however, is the mechanism of asymmetric division understood.  Here I propose a model for the mechanism of asymmetric division during sporulation in Bacillus subtilis.  The model explains both the timing and asymmetric localization of spore-septum formation.  It also explains the morphological phenotypes of various asporogenous (spo) mutants.