Matthias Jakob Schleiden (1804-1881)
Matthias Jakob Schleiden was Professor of botany at the University of Jena and is best known as one of the foundational architects of the cell theory. Schleiden was also an early evolutionist. As Schleiden wrote in a lecture on the “History of the Vegetable World” published in The Plant; A Biography, 1848 (translated into English by Arthur Henfrey), “We know that varieties once formed, when they have continued to vegetate under the same conditions for several generations, pass into sub-species; that is, into varieties which may be propagated with certainty by their seeds. How, then, if the same influences which have called forth an aberration from the original form of the plant, continue to act in the same way, not for centuries or tens of centuries, but for ten or a hundred thousand years, will not at last, as the variety thus becomes a sub-species, so also, this, become so permanent, that we shall and must describe it as a species. Then, if the first cell be given, the foregoing points out how the whole wealth of the vegetable kingdom may have been formed by a gradual passage from it through varieties, sub-species and species, and thus onward, beginning anew from each species – in a space of time, indeed, of which we have no conception.”
Baden Powell, in his book on evolution (1855), quoted from The Plant to support his transformist views. Ironically, when Charles Darwin was working with Heinrich Georg Bronn to arrange for a German translation of On the Origin of Species in 1860, he wrote “I am not much acquainted with German Authors as I read German very slowly. Therefore I do not know whether any Germans have advocated similar views with mine; if they have would you do me the favour to insert a footnote to the Preface?” Bronn did not supplement Darwin’s historical preface. Thus, even though Schleiden’s evolutionary views were published in English, he never was cited by Darwin as an early evolutionist.