February, 1911. 



KNOWLEDGE. 



69 



can reach perfection, the verdicts of the Committee have 

 always met with the approval of the astronomical world, and 

 received unanimous praise. 



Once a year, generallj- in the month of November or so, the 

 Committee publishes, in the Axtronoiiiische Xacliriclitcii. 

 a list of lettered variables, giving in tabular form, their name, 

 provisional number, position for 1855.0 and 1900.0, value of 

 precession, magnitudes at maximum and minimum, and 

 indication whether these magnitudes are visual or photo- 

 graphical. This list is supplemented by notes giving refer- 

 ences to catalogues ("Bonner Durchmusterung," or "'A.G." 

 numbers), indicating the name of the discoverer and 

 "supporter," and giving a short historical sketch, with 

 elements, colour, and other notes. 



(2) The Astronomische Nacliriclitcn (.4.A'.), the lead- 

 ing astronomical paper of the world, is published at Kiel 

 (Schleswig-Holstein), at the rate of one or two numbers, 

 generally of eight pages (or si.xteen " columns " as they are 

 numbered) a week, twenty-four numbers forming one volume. 

 The character of this paper is thoroughly international and, 

 though many papers are printed in the German language. 

 French, English, Italian, Spanish, and even Latin memoirs 

 are not uncommon. The Astroiioniisclie Xachrichten. 

 founded by H. C. Schumacher, in 1821, September, and 

 therefore the oldest amongst astronomical journals, is about to 

 publish its one hundred and eighty-seventh volume Icomnienc- 

 ing with Xo. 4465, issued 1911, January 12thl, and is under 

 the editorship of Professor Dr. Hermann Kobold, astronomer 

 at the Observatory of Kiel's University, who also directs the 

 Cciitralstelle for the centralization and circulation in 

 Europe of astronomical news. The collection of this paper 

 includes also seventeen more or less extensive complementary 

 numbers or Ergaiiznngshefte and six general tables of 

 contents, a seventh being in course of preparation, as well as 

 reprints of some old volumes. 



The Astronomische Kachrichtcn contains the greatest 

 part of variable star information and has, for a long 

 time, been the medium through which new discoveries 

 of these objects are announced to the world. In 

 order to avoid confusion and to permit easy references. 

 Professor Kreutz, the fourth editor of the paper (the 

 first was Schumacher), decided, in 1900, to affix a " pro- 

 visional number" to new variables, pending their definitive 

 lettering by the "A.G." Committee. This series of numbers is 

 begun again every year, from No. 1, the name of the year being 

 affi.xed to the number. So, for example, 



BD + 7 929 = 47.1910 Orionis=RT Ononis. 



This is a similar method to that followed for new 

 asteroids, save that a reverse system is in use ; newlj-- 

 discovered small planets receive a double letter with the 

 year prefixed, and are afterwards numbered and named. 



(3) Some years ago the " Astronomische Gesellschaft." 

 represented by its committee on variables, decided to compile 

 and pubhsh a great catalogue of these objects. As will be 

 seen afterwards, works of this kind have been planned and 

 partly printed elsewhere, but it may be confidently assumed 

 that the bibliographical task now undertaken in Germany will 

 go far beyond all that has been done till to-day, and will 

 form a standard work, whose value, as it approximates to 

 completeness, can hardly be overrated. 



The catalogue will be divided in four great sections: — 1(tI 

 Variable stars; (6) Suspected variable stars; (c) Variable 

 stars in clusters; (d) New or temporary stars; dealing with 

 one thousand objects. Other somewhat abridged mono- 

 graphs will deal with newly-discovered variables, for which 

 the available material of observation is less abundant. The 

 work will give for each variable the '" complete" bibliographical 

 sources and references, and a thorough discussion of all 

 published (and, in many cases, unpublished) data. It will not 

 include however, some well-known variables on which com- 

 plete monographs have already been published, such as 

 Mira Ceti (Guthnick), x Cygni (Rosenberg), 5 Librae iKron), 

 R Coronae (Ludendorf) and U Geminorum Ivan der Biltl. 



The discussion of this formidable material, always kept up 

 to date, has been divided among a number of fellow-workers. 

 At the time of writing, the MSS. for seven hundred stars is 



ready, two hundred are under discussion, and one hundred 

 are still in abeyance. In the course of its twenty-third meeting, 

 recently held in Breslau (see " Knowledge," 1910, November 

 and December), the Society voted a sum of 1,000 marks (i,50) 

 towards the continuation of the work, and 10,000 marks 

 (£500) towards the cost of printing the first part, which may 

 be expected to appear in the course of the present year. 



Felix de Roy, 

 Honorary Secretary " Societe d'Astror:o:iiie d'Anvers." 



( To he continued.) 



BOTANY. 



By Professor F. C.-wers, D.Sc. 



EOCENE FLORAS. — In a recent paper on "An Eocene 

 Flora in Georgia, and the Indicated Physical Conditions," 

 Berry iBot. Gaz., vol. 50, 1910), draw-s an interesting 

 comparison between the Eocene floras of Em'ope and 

 North America. The Middle Eocene floras of North America, 

 like those of Europe, show distinctly tropical characters, 

 which are absent in the earlier or Lower Eocene. These 

 chiiracters first become marked in the fruits from the London 

 Clay and the leaves from Alum Bay, and in corresponding 

 deposits on the Continent. These floras show much closer 

 affinities with the modern floras of Malaysia and tropical 

 .America than with those of Australia — the supposed 

 Australian affinities of the Eocene floras may now be regarded 

 as an exploded myth. The Eocene genus Nipadites 

 corresponds exactly with the modern Palm genus Nipa. which 

 inhabits the tidal waters of the Indian Ocean, and ranges 

 from India, through the Malay Archipelago, to the Philippines. 

 The Xipa sv\amps of the Eocene period ranged northwards in 

 Europe to southern England, and though Nipadites does not 

 occur (so far as known) in the Eocene of America, the latter 

 shows various forms, either identical with, or allied to, the 

 plants associated with Xipcidifes in the Eocene of Europe, 

 including various tropical Ferns. The existing flora of 

 Florida, the Bahamas and Bermuda contains a large element 

 which has been derived in comparatively recent geological 

 times from the south, but the main elements of these modern 

 floras were already in existence in the Middle Eocene, if not 

 earlier. There is abundant e\ idence that nearly all modern 

 plant families, excepting such specialised forms as the 

 Orchidaceae among Monocotyledons and the Compositae and 

 their allies among Dicotyledons, were at one time more widely 

 distributed than they are at present, and that the details of 

 modern geographical distribution represent in a less degree 

 the interchange of types between different areas than they do 

 the greater or less degree of segregation of descendants of 

 forms once spread over much wider areas. The strictly 

 modern mo\ement of the subtropical flora along the course of 

 the Gulf Stream has been from the south, northward, as the 

 various coral islands of the Bahamas became evolved. This 

 dispersal was preceded by a similar spread of the tropical 

 flora on a much more extended scale during the early Tertiary. 



AFFINITIES OF CACTACEAE.— The Cactaceae have 

 attracted a large amount of attention recently. A special 

 German journal has been founded to deal exclusi\ely with 

 this family of plants, and some interesting observations and 

 speculations have been made by \arious writers regarding the 

 affinities of the family and its position in the natural system. 

 The Cactaceae have for long been regarded as an isolated 

 group of obscure affinities, and in different systems of 

 classification they occupy very ^-arious positions. Although 

 the Cactaceae are highly specialisedasregards their vegetative 

 characters, there are many features in their floral structure 

 that indicate affinities with the cohort Kanales, w^hich includes 

 the orders Nymphaeaceae (Water-Ulies), Magnoliaceae (Tulip- 

 tree, and so on), and Ranunculaceae, besides others. The 

 most striking of these " Ranalian " characters are : (1) the 

 numerous spirally arranged sepals, petals, stamens, and 

 carpels : (2) the occurrence in some cases of a gradual 

 transition from sepals to petals ; (3) the insertion in some 

 cases of the sepals and petals on the outer surface of a 

 receptacle cup in which the carpels are embedded. There is 



