90 STRUCTURE AND DEVELOPMENT OF MOSSES AND FERNS. writers. In carrying out this aim he iias made manifold additions to the sum of our knowledge ; and his new book is to be regarded as a fresh investigation of the group, with the gaps in the author's observations filled in from the work of others. The result is a vast array of facts, clearly stated, systematically and intelligently arranged, and admirably illustrated ; and upon a wise and clear- sighted consideration of these facts an attractive theory has been built up as to the evolution and phylogenetic affinities of the Mosses, Ferns, and Flowering Plants. The abundant figures are for the most part new, and were drawn by the author himself; they are placed where they are of most assistance to the reader, viz., in the text which they illustrate. The book may be described as the outcome of the improved microscopic methods of the present day, and as a brilliant example of the results obtainable by a skilful operator. Eeaders may be interested to know that Mr. Campbell has presented a large series of his microtome prepara- tions to the British Museum. Systematists will doubtless quarrel with Mr. Campbell's novel classification of some of the families. However, it is not a matter of much moment what classification is adopted in an avowedly morphological treatise. The present arrangement is a suggestive one, and enables the author to emphasize certain affinities or resemblances which have not hitherto been brought out so strongly, and which may possibly in days to come lead to alterations in the classification at present accepted by systematists. It is not possible in the limits of this notice to represent at all adequately the amount of ground covered by the author. That must be left to the individual reader to ascertain. But the attention of the latter may profitably be called to several points of interest. The partitioning of the book is as follows : — Four chapters are allotted to the Hepatics, two to the Mosses, five to the FilicinecB, and to the Kquisetinem and Lycopod'mece one each. In the natural orders of each class the life-history and morphology of selected types are described in detail, beginning with the germination of the spore, and passing through the gametophyte (sexual generation) to the sporophyte (non- sexual generation) in its embryonic and mature stages, until in the subsequent spore-formation the cycle is com- pleted. Deviations exhibited by other genera are also discussed. The Hepatics are treated in three groups : — (1) MarchantiacecB, characterised by a specialisation of their gametophyte tissues ; (2) JimgernianiiiacecE, characterised by a development of appen- dicular organs ; (3) Anthocerotea (Mr. Campbell's pet subject), characterised by the simplicity of the gametophyte and the highly difierentiated sporangium. This latter group is shown to be of extraordinary morphological interest, as connecting the other Hepatics with the Mosses (through Sphagnum) on the one hand, and the eusporangiate Ferns (especially Ophioglossum) on the other. The points of resemblance are several, and are properly and fully insisted upon by the author. Passing over the Mosses, which are regarded as a divergent group which has specialised itself to meet the requirements of
