Unravelling the life cycle of ‘Polystomella crispa’: the roles of Lister, Jepps and Myers
Keywords: foraminifera, dimorphism, life cycle, history of research
Abstract. The meticulous observations of Lister, Jepps and Myers involved the culturing of material, monitoring the behaviour of live individuals over periods of days and weeks and at different times of the year, and decalcifying tests in order to stain and examine the protoplasmic contents with the best available microscopes. They all based their studies at the Laboratory of the Marine Biological Association in Plymouth and Myers and Jepps overlapped in the early 1940s although they chose to work separately. Through their combined efforts they determined that the life cycle of Elphidium crispum (Linné) (formerly called Polystomella crispa) involves an alternation of generations, sexual and asexual, over a two-year period. This has remained the ‘classic’ life cycle of benthic foraminifera, although subsequent studies, including those of Myers, have revealed other patterns. Lister also established that test dimorphism is not related to sex but to the asexual and sexual phases of reproduction.