The past 50 years have witnessed the explosive development of genetics and physiology both as separate disciplines and as applied to mycology. In physiological terms we have seen the transition from the lag phase to the logarithmic phase of the development of these disci? plines. Paradoxically, perhaps, the more intensively these have been studied the more their boundaries have blurred and merged and the more their data have coalesced with those of their sister fields of mor?