CHAP, in.] 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 thick- 

 ness, which Endlicher borrowed from Unger. While End- 

 licher'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 de- 

 vised by JOHN LINDLEY* 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 (pa- 

 rallel-nerved Monocotyledons); (3) Dictyogens (net-veined 

 Monocotyledons) ; (4) Gymnogens (Gymnosperms) ; (5) Exo- 

 gens (Dicotyledons). This classification is one of the most un- 

 fortunate 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. 

 L 2 



