His model, the "Stammbaumtheorie" (family-tree theory), was a major development in the study of Indo-European languages. He first introduced a graphic representation of a "Stammbaum" in an article published in 1853 entitled "Die ersten Spaltungen des indogermanischen Urvolkes". By the time of the publication of his "Deutsche Sprache (German language)" (1860) he had begun to use trees to illustrate language descent. Schleicher is commonly recognized as the first linguist to portray language evolution using the figure of a "tree". Largely in reaction, Johannes Schmidt later proposed his 'Wave Theory' as an alternative model.