those of his master, and the worst of these is his large work 'Von der Sexualitat dor Pflanzen' of 1820. He thought himself obliged to prove the doctrines of the nature-philosophy by countless experiments; but the way in which these are devised, managed and described displays the extreme of dulness and incapacity to form a sound judgment. The doubt which must
occasionally rise in the mind of the reader as to the accuracy
of his reports, and the remarks which have been made on this
point by Treviranus and Gartner, are not needed to disgust
him with the scientific efforts of this writer.
It would be superfluous to give an account of the contents of Henschel's book, which is interesting from the pathological rather than from the historical point of view. To what an extent better men than Henschel even later than 1820 lost under the influence of the nature-philosophy their capacity for judging such questions as we are discussing, how even investigators of merit thought it worth while to treat the productions of Schelver and Henschel with a certain respect, is shown among other works, by a collection of letters, which were published by Nees von Esenbeck as a second supplement to the 'Regensberg Flora' of 1821, and by the later remarks of Goethe on the metamorphosis of plants, to be found in Cotta's edition of his works in forty volumes (vol. xxxvi. p. 134) under the title 'Verstaubung, Verdunstung, Vertropfung.' But there were some who set themselves distinctly against these pernicious ideas, such as Paula Schrank ('Flora,' 1822, p. 49) and C. L. Treviranus, who published in 1822 a full refutation of Henschel in his 'Lehre von dem Geschlecht der Pflanzen in Bezug auf die neuesten Angriffe erwogen.' A few stray supporters of the dying nature-philosophy were still to be found at a later time; among them Wilbrand, Professor in Giessen, who ('Flora,' 1830, p. 585) adopted the very subtle distinction that there is in plants something analogous to sexuality in animals, but no real sexuality. We see in the whole literature of the nature-
