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 Hirszfeld was the first to foresee the serological conflict between mother and child, which was confirmed by the discovery of the Rhesus factor. Upon this basis he developed, in the last years of his life, an "allergic" theory of miscarriage and recommended antihistamine therapy. Hirszfeld also investigated tumors and the serology of tuberculosis. His discovery of the infectious agent of paratyphoid C had far-reaching consequences for differential diagnosis. 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