Interlinguistics of interlinguistics are, however, not so constructive, but rather descriptive, comparative, historic, sociolinguistic, or concerned with translation by humans or machines. As for Esperanto, which is the most widely used constructed interlanguage, there is a relatively abundant literature about the language itself and its philology (see Esperantology). Only a few of the many constructed languages have been applied practically to any noteworthy extent. The most prosperous were Volapük (1879, Johann Martin Schleyer), Esperanto (1887 Ludwik Lejzer Zamenhof), Latino sine flexione (1903, Giuseppe Peano), Ido (1907, Louis Couturat), Occidental-Interlingue (1922, Edgar de Wahl) and Interlingua (1951, IALA and Alexander Gode), with
Ludwik Hirszfeld Ludwik Hirszfeld Ludwik Hirszfeld (5 August 1884 in Warsaw – 7 March 1954 in Wrocław) was a Polish microbiologist and serologist. He is considered a co-discoverer of the inheritance of ABO blood types. He was a cousin of Aleksander Rajchman, a Polish mathematician, and of Ludwik Rajchman, a Polish bacteriologist. After attending the Gymnasium in Łódź, Hirszfeld, born into a Jewish family and later a convert to Catholicism, decided to study medicine in Germany. In 1902 he entered the University of Würzburg and transferred in 1904 to Berlin, where he attended lectures in medicine and philosophy. Hirszfeld completed his doctoral