Johann Flo ¨gel (1834–1918) and the birth of comparative insect neuroanatomy and brain nomenclature Nicholas J. Strausfeld a, * , Ernst-August Seyfarth b a Arizona Research Laboratories, Division of Neurobiology, 611 Gould-Simpson, University of Arizona, Tucson, AZ 85721, USA b Institut fu ¨r Zellbiologie & Neurowissenschaft, J.W. Goethe-Universita ¨t, Siesmayerstrasse 70, D-60054 Frankfurt am Main, Germany article info Article history: Received 17 February 2008 Accepted 28 February 2008 Keywords: Neuroanatomy Insect Nomenclature History of science Biography abstract Johann H.L. Flo ¨gel (1834–1918) was an amateur scientist and self-taught microscopist in Germany who 130 years ago pioneered comparative arthropod neuroanatomy. He was fascinated by innovations in optical instrumentation, and his meticulous studies of the insect supraoesophageal ganglia were the first to use serial sections and photomicrographs to characterize the architecture of circumscribed regions of brain tissue. Flo ¨ gel recognized the interpretative power resulting from observations across various species, and his comparative study of 1878, in particular, provided a baseline for subsequent workers to evolve a secure nomenclature of insect brain structures. His contributions stand out from contemporary accounts by virtue of their disciplined descriptions and emphasis on identifying comparable elements in different taxa. Here we give a biographical sketch of his life and summarize his remarkable achievements. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction A stable anatomical nomenclature originates from a set of clearly defined terms, the subsequent alterations of which result from new data rather than the whims of an investigator. Novel methods, new insights about developmental processes, and func- tional studies can all redefine previously named structures. How- ever, as is evident from the plethora of terms used in vertebrate neurology (see, for example, the discussion by Swanson, 2000), alternate terms denoting the same entity hinder communication and slow the progress of science. Insect brain research has been more fortunate in that the invention of names has overall been relatively free of ambiguity. From the outset, names were used that signified familiar constructs, such as ‘‘the beam’’ (‘‘Balken’’ in German) for a structure that was massive and which appeared to support elements above it. This early clarity was the achievement of a nearly forgotten scientist from Germany: Johann Flo ¨ gel, a self- taught microscopist who a hundred and thirty years ago pioneered comparative neuroanatomy. 2. Biographical sketch Johann Heinrich Ludwig Flo ¨gel was born in 1834 in Glu ¨ ckstadt/ Holstein, in northern Germany. He trained as an administrative lawyer, and later pursued a modest career as a municipal notary public and tax official (‘‘Kirchspielvogt’’) in Bramstedt, near the coastal city of Kiel. Apparently, his duties left him enough spare time to pursue serious scientific research. In 1889, due to admin- istrative government reforms, he chose early retirement from his office and (at the age of 55) settled in Ahrensburg, not far from Hamburg. He became what is known as a ‘‘Privatgelehrter’’ – a self- motivated researcher funded by private means – who developed a passion for studying natural phenomena. Two studies of the microscopy of diatoms resulted in him becoming a member of a maritime survey of the Baltic Sea. He purchased microscopes and telescopes, all built according to his own specifications, so he could indulge in both meteorological and microscopical observations (see the portrait in Fig. 1 , left). He published on cloud formation, the aurora borealis, and the microscopic structure of hail and snow. All of these studies were recognized as highly professional and they earned him an honorary doctorate in 1875 from the University of Kiel. His studies were reported in contemporary Proceedings of the Royal Microscopical Society (1883, p. 969), which reviewed the design of his specially constructed darkroom and his novel use of photography to capture photographic images of histological preparations and commented on his use of paraffin wax for embedding. In 1885, he was made an honorary Fellow of the Royal Microscopical Society of London on the basis of his anatomical studies, which are summarized here. Flo ¨gel was intrigued by minutiae. Of the living, he favored the insects, because they offered extraordinary and microscopic detail. At first glance, his neuroanatomical publications seem modest, a mere two papers. However, they are pivotal to almost all * Corresponding author. Tel.: þ1 520 621 8382; fax: þ1 520 621 8282. E-mail address: flybrain@neurobio.arizona.edu (N.J. Strausfeld). Contents lists available at ScienceDirect Arthropod Structure & Development journal homepage: www.elsevier.com/locate/asd Arthropod Structure & Development 37 (2008) 434–441 Contents lists available at ScienceDirect Arthropod Structure & Development journal homepage: www.elsevier.com/locate/asd 1467-8039/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.asd.2008.02.003