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Chap. III.]
the Dogma of Constancy of Species.
147

and Cycads), Amphibrya (Monocotyledons), and Acramphibrya (Dicotyledons and Conifers); the names of the three latter groups, the first of which is utterly unnatural, are founded on erroneous assumptions respecting growth in length and thickness, which Endlicher borrowed from Unger. While Endlicher's great work has continued down to our own time to be indispensable to the botanist as a book of reference on account of the fulness of its descriptions of families and genera, the system projected by Brongniart in 1843 has acquired a sort of official authority in France. The whole vegetable kingdom is here distributed into two divisions, Cryptogams and Phanerogams, and the former are incorrectly characterised as asexual, the latter as having distinction of sex. The Phanerogams, divided into Monocotyledons and Dicotyledons, are distributed into groups in a manner that is not satisfactory; but the system has one merit, that it keeps the Gymnosperms together in one body; and if they are incorrectly classed with the Dicotyledons, it was still a sign of progress, that Robert Brown's discovery of gymnospermy was to some extent practically recognised. The system devised by John Lindley[1] attained to about the same importance in England as attached to those of Bartling and Endlicher in Germany, and that of Brongniart in France. After various earlier attempts he proposed a system in 1845, in which, as in Brongniart's arrangement, the Cryptogams are characterised as asexual or flowerless plants, the Phanerogams as sexual or flowering plants; the former are divided into Thallogens and Acrogens, the Phanerogams into five classes; (i) Rhizogens (Rafflesiaceae, Cytineae, Balanophorae); (2) Endogens (parallel-nerved Monocotyledons); (3) Dictyogens (net-veined Monocotyledons); (4) Gymnogens (Gymnosperms); (5) Exogens (Dicotyledons). This classification is one of the most unfortunate that were ever attempted; the systematic value of the


  1. John Lindley, Professor of Botany in the University of London, was born at Chatton near Norwich in 1799, and died in London in 1865.