100 Years of Research on 'Turbellaria'

Comprehensive research on the 'Turbellaria' - or what are known now as the free-living platyhelminths - can mark its beginnings with the first monogra phic treatises on the group, foremost those by v. Graff, Lang, Wilhelmi and Benham. A major center for turbellarian research grew up around Graff in G raz, Austria, from 1884 through the first quarter of the 20th century; amon g its members were Bohmig, A. Meixner, J. Meixner, Reisinger and Steinbock. Other contributors to the major research effort in the later years of the 19th and early part of the 20th century were scattered in Germany, Italy, F rance, Scandinavia, Russia, Japan and the United States and included Hofste n, Steinmann, Wilhelmi, Sabussov, Beauchamp, Bresslau, Beck, Kenk, Ijima an d Kaburaki. The attention to detail and accuracy of presentation by these e arly workers in Graz and elsewhere has made their contributions of long-las ting value. Between 1910 and 1960, modern research whose impact is still wi dely felt today took form. It includes studies in systematics (Luther, Karl ing, Hyman, Meixner, Beauchamp, Ijima, Ivanov, Mamkaev, Kenk, Papi, Riedl, Marcus, Ax), development (Bresslau, Reisinger, Steinbock), physiology (Hyma n, Westblad), and genetics (Benazzi). Electron microscopy had a profound im pact on morphological study starting in the 1970's, and the data it provide d led to a new phylogenetic system of the Platyhelminthes as a whole, empha sizing the paraphyletic nature of the 'Turbellaria' within it. Systematic b iology can be expected to make further advances by combining molecular meth ods with high-quality traditional taxonomic ones, still essential to this f ield. Other methodological advances spurring turbellarian research today in clude immunocytochemistry, molecular biology of nucleic acids, karyology an d computational methods. Better understanding of nervous systems and muscle systems should come through studies in functional biology, immunocytochemi stry, fluorescence microscopy and molecular biology. Understanding the earl y evolution of the brain as a control center in the nervous system will be especially interesting. Studies of structural and regulatory proteins as we ll as the newer microscopical techniques should provide insight into the re gulation of cell proliferation, tissue growth, and embryonic development. E cology and behavior are areas in which research efforts should be intensifi ed. Culturing and the new techniques in molecular biology, microscopy and c omputational methods now allow the collection of quantitative, experimental data in these fields. Current karyological and biogeographical studies as well as work on the evolution of sex in hermaphrodites are encouraging sign s that we might soon better understand many aspects of reproduction and of interactions of free-living platyhelminths in their ecosystems. Turbellaria ns remain important research subjects for reasons that inspired interest by even the earliest workers, the probability that they are the most primitiv e living representatives of the Bilateria.