September 7, 191 1] 



NATURE 



509 



phyla; (iv) Phaeophyta ; (v) Rhodophyta ; (vi) Euthallo- 

 phyta ; and (vii) ("ormophyta ; and he thinks it very 

 probable that the Cormophytes may have been derived 

 from one or the other of these stems, most probably 

 from the Euthallophyta. The designation of these 

 stems are mostly sufficiently descriptive to be intelli- 

 gible ; but one is naturally curious as to what the 

 Euthallophyta include, as they are here placed next to 

 the Cormophvta, on account " of possible genetic con- 

 nections." YVettstein's brief diagnosis of this group 

 runs : — 



" One-celled or many-celled. Cells of the vegetative 

 stages of development, clothed by a membrane, which 

 is not composed of shell-like segments. Autotrophic 

 (self-nourishing) or (in derived series of forms) hetero- 

 trophic. The autotrophic forms always furnished with 

 chlorophyll in the assimilating cells. Simpler forms 

 propagated vegetatively only ; those of higher organisa- 

 tion sexually as well. Autotrophic forms (with isolated 

 exceptions) adapted to the development of their repro- 

 ductive organs in water. Not differentiated into root, 

 stem, and leaf." 



It is not assumed that the above characteristics 

 (all or any one of them) are peculiar to the group ; 

 but as thus broadly defined, the Euthallophyta 

 include two classes, the Chlorophyceaj and the Fungi. 

 To the first belong the orders Yolvoceas, Ulothricaceae, 

 Siphoneas, and the Characeae. The Fungi are divided 

 into parasitic and saprophytic Fungi, including those 

 symbiotic with Cormophytes (Mycorrhiza, &c), and 

 Fungi symbiotic with Algae, otherwise Lichens. The 

 Myxophyta, formerly associated with Fungi, and now 

 placed in the lowest series of vegetable organisms, are 

 characterised thus : — 



" One-celled or many-celled. Vegetative stages of 

 development composed entirely of membraneless cells. 

 Nourishment never autotropic. Sexual reproduction 

 altogether wanting." 



We have not space to enlarge on the treatment of 

 the different groups of organisms; but it may be men- 

 tioned that the Schizomycetes (bacteria) are described 

 and illustrated in some detail, though the figures are 

 practically all copied from Migula, Meyer, and other 

 writers on the subject, and are much the same as in 

 the first edition. 



It may be interesting to mention that the cells of 

 some of the Schizomycetes are the smallest hitherto 

 measured; those of Spirillum parrum being from o'l to 

 03 fj, in thickness, whilst those of the organism 

 causing lung-disease in cattle are described as even 

 smaller. 



Turning to the Gymnospermae. It seems a pity that 

 the term " flower " should still be employed to designate 

 the organs of reproduction, with or without envelopes 

 or appendages, especially as the interpretations of 

 authors are so divergent ; some viewing the female 

 cone of an Abies, for example, as an inflorescence, 

 others as a flower. Much confusion has arisen from 

 this cause in the nomenclature of the components of a 

 cone. Wettstein defines the flowers, "characteristic of 

 all Anlhophytes," as shoots, or parts of shoots, which 

 bear the leaves on which the sexual organs of repro- 

 duction are formed. And he adds that accepting this 

 NO. 2184, VOL. 87] 



definition, Selaginella is the only other genus among 

 recent plants that has flowers In this connection it 

 may be added that the fossil Bennettitinae present 

 some of the most singular of the " flowers " of Gymno- 

 sperms. They are either unisexual or bisexual. Those 

 of Cycadeoidea ingens are interpreted as having a 

 perianth of numerous plumose segments ; twelve 

 pinnate stamens, involute in aestivation, with very 

 numerous anther-cells, and a solitary central gynaeceum 

 or ovule, whereas C. Wielandii has female " flowers " 

 with a plumose perianth and numerous separate 

 ovules, or gynaecia, looking much more like pistils. 



Tumboa (Welwitschia) is mentioned as the only 

 living gymnosperm in which the pollen is conveyed 

 by insects to the ovules. 



The foregoing was written before the second part 

 of the work was received. This has undergone less 

 modification than the first, and we must dismiss it 

 with a few words. We note that the proposed new 

 Order or Family, the Julianiaceae, has been accepted 

 and placed in the Juglandales, though Hallier had 

 previously reduced it to the Terebinthaceae. The entire 

 work has undergone an enlargement from 778 pages 

 to 914, with 571 additional figures. Most of the figures 

 are exceedingly good, but unfortunately many of them 

 have lost much of their beauty through being printed 

 too black. Of course, in a comprehensive work like 

 the present, a large proportion of the figures must be 

 borrowed ; but here the source of every one is indi- 

 cated. It may be added that Dr. Wettstein writes a 

 simple, clear German which is easilv construed. 



YV. B. H. 



PHOTOMICROGRAPHY. 

 Practical Photomicrography. By J. E. Barnard. 

 Pp. xii + 322+10 plates. (London: Edward Arnold, 

 191 1.) Price 155. net. 



KING SOLOMON'S remark that "of making 

 books there is no end," applies to the subject 

 of Photomicrography nowadays, as well as to any 

 subject in his time, for many indeed are the books, 

 both large and small, that are now available. Yet 

 the author of "Practical Photomicrography" has 

 had the courage to publish a handsome volume of 

 some 300 pages which we think fills a unique place. 

 Our reason for saying so is because we should 

 call this book a dictionary upon the subject rather 

 than a practical guide, and there is no such work 

 as that in existence. For example, if we require 

 an illuminant suitable for some special class of work, 

 we have only to turn to our dictionary, open the 

 chapter devoted to "sources of illumination," and 

 there we find an epitome of all that is known upon 

 the subject. So, too, with cameras for all classes of 

 work, photographic stands, and, indeed, every other 

 thing connected with photomicrography. But if we 

 look for practical hints or useful "dodges," such as 

 the author must know in abundance, we can find — 

 if, indeed, any at all— only a very meagre supply. 

 There is no taking the beginner by the hand when 

 attempting his first photograph, and telling him how 



