282 



NA TURE 



\_7uly 2 2, 1880 



gamic Lycopod, and the other a Gymnosjermous Sigillaria. The 

 remarkable peculiarities characterising the central axis of these 

 specimens make it absolutely certain that they all belong to one 

 species of plant. 



The typical Lepidodendron Hanourtii is then examined in a 

 similar manner. In the details of its organisation it differs ma- 

 terially from L. Selaginoidcs ; nevertheless, as its growth pro- 

 gresses, it displays typically similar changes. It attains to much 

 larger dimensions than the latter plant does before developing its 

 exogenous zone, corresponding in this respect with the Arran 

 plant. Its earlier changes are chiefly seen in the rapid develop- 

 ment of the bast or prosenchymatons layer of the outer bark and 

 in the increase in the size and number of the vessels constituting 

 its vasculo-meduUary cylinder or mediiUary sheath — the " iiut 

 meduUaire " of Brongniart ; but in more advanced specimens a 

 cylindrical zone of centrifugally developed vascular wedges 

 begins to make its appearance in a quasi-cambian zone of the 

 cells of the inner bark, these cells being arranged in more or Ic s 

 regular radiating line=. In this state the rudimentary vascular 

 zone corresponds very closely to what is seen in young stems 

 and roots of Cycads. 



The author shows that, contrary to the views of M. Renault, 

 very marked changes take place in the development of the 

 vascular bundles destined for the secondary branches of the 

 plant. In the first instance, each of these is but a concavo- 

 convex segment of the entire vasculo-meduUary cylinder, whose 

 detachment leaves a large gap in the continuity of that cylinder, 

 which, however, soon becomes closed again by the convergence 

 of the disconnected ends of the broken vascular circle. The 

 concavo-convex detached segment undergoes a similar change. 

 Its two extremities meet, and before it escapes from the outer- 

 most bark it has assumed the cylindrical form of its parent stem. 

 The rootlets of Sti^maria Jiccides, now well known to belong 

 alike to Lepidodendron and to Sigillaria, present some pecu- 

 liarities of structure which are only found in the Lycopodiacece 

 and the Ophiogloss.-e, amongst living plants. 



The vascular bundle in the interior of each Stigmarian rootlet 

 is inclosed within a very regularly circular cylinder, composed of 

 the cells of the innermost bark ; but the position of the bundle 

 in relation to the cylinder is always, unless accidentally dis- 

 turbed, an eccentric one. This position has not escaped notice, 

 but it was regarded as accidental ; it now, however, proves to 

 be a normal one. The bundle begins to appear in very young 

 roots, as one or t« o very small vessels developed in close union 

 with the innermost cells of one side of the cylinder within \\liich 

 it is located ; newer and larger vessels are gradually added 

 centripetally, until the bundle occupies a considerable portion of 

 the area inclosed by the inner bark cylinder. The remaining 

 space is usually empty, but occasionally specimens are found in 

 which it is filled with small delicate cells that have escaped 

 destruction. These represent what in the living Lycopods are 

 liber-cells. The outer cortical layer of the root, composed of 

 well-preserved and rather thick-\\alled cells, is usually separated 

 from the inner cylinder by a similar lacuna ; but in a few 

 specimens the cells of this usually destroyed middle bark are 

 retained in good preservation. They consist of very delicate 

 thin-walled parenchyma, separated by a sharp line of demarcation 

 equally from the innermost and outermost cortical cylinders. 

 The number of the vessels in each of the vascular bundles given 

 oft" from any one section of a Stigmarian root is found to vary 

 but little, but they steadily increase, both in number and size, 

 with the size and age of the root. Young specimens of Stig- 

 marian roots are described, the smallest of which is not more 

 than one-fifth of an inch in diameter, and the vascular bundles 

 of its small rootlets consist each of from three to five minute 

 vessels. In the largest rootlets from old roots they number 

 about forty, most of the additional ones being of larger size ; 

 intermediate examples exhibit a regular gradation on all these 

 points. 



The only living plants which possess rootlets with this struc- 

 ture being Lycopodiacea; and Ophioglossre, and it being suffi- 

 ciently clear that the Lepidodendra belong to the former .and not 

 to the latter order of cryptogams, the existence of this Lyco- 

 podkaceous feature in the rootlets of Sigillaria is another 

 indication of the Lycopodaceous affinities of these plants. 



Many of the Diploxyloid forms of the Lycopodiaceous stems of 

 the coal-measures have an abundant development of spiral or 

 barred cells in their numerous medullary rays. Amongst living 

 plants this characteristic seems to be almost, if not wholly, 

 confined to the Gymnosperms. 



Two important additional observations have been made in 

 reference to the structure of the curious strobilus, Calamostachys 

 Binncyana. The exact mode of the attachment of its sporangia 

 to the Equisetiform sporangiophores has been ascertained ; but 

 what is still more important, it has also been discovered that it 

 is provided with both micro- and macro-spores — an additional 

 indication of its probable Lycopodiaceous affinities, already 

 suggested by other features of the fruit. 



The recently discovered Fungi of the coal-measures are investi- 

 gated, especially the Pernosporites antiquiorum of Mr. Wortliing- 

 ton Smith. The author finds, in the specimens he has examined, 

 including that described by Mr. Smith, no traces of septa in the 

 kyphoe or of zoospores in the Oogonia. He concludes that its 

 affinities are probably with the Saprolegnis, and not with the 

 Pernosporeee. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 

 The Professorship of Zoology in the Royal College of Science, 

 Dublin, is vacant by the resignation of Prof. Bridge. The 

 salary is 200/. a year, and at present the professor is only 

 required to lecture during one term, commencing in February 

 and ending in June. 



The University Court of St. Andrews have elected Mr. Arthur 

 Stanley Butler, B.A., of Exeter College, Oxford, to the Chair 

 of Natural Philosophy in the United College, St. Andrews, in 

 the room of Dr. William Swan, resigned. 



\\, The Calendar of the University College of Wales for 1879-S0 

 shows that that institution is fairly well equipped in its various 

 departments, science occupying a prominent place in its 

 curriculum. 



At the end of the Legislative Session the French Chamber of 

 Deputies voted a law establishing free primary education. It 

 must go through the Upper House before becoming a definitive 

 Law of the State. 



SCIENTIFIC SERIALS 



The AmcHcan Na/nralist, June. — A. E. Ero«n and J. D. 

 Caton, the domestication of certain ruminants and aquatic birds. 

 J. S. Lippincott, the critics of evolution (concluded). — C. E. 

 Bessey, the supposed dimorphism of Lithospcriinim longiflortim 

 (the large flowers appear from April to May, the cleistogamous 

 flowers from then until the autumn frosts). — Dr. J. Leidy, on 

 some aquatic worms of the family Naides (describes and figures 

 Dcro limosa, perhaps --= D. digitata, Oken ; Aiilop/wriis vagus, 

 this forms a tube of the statoblasts of a species of Plumatella, 

 and Pristiua flagellum). — W. H. Dall, American work in the 

 department of recent mollusca during 1879. 



July. — G. Brown Goode, the use of agricultural fertilisers by 

 the American Indi.ans and the early English colonists (contains 

 some interesting factsabout fish manures). — C. S. Minot, sketch 

 of comparative embryology (The Sponges). — O. B. Johnson, 

 the birds of the Willamette Valley, Oregon. — J. F. James, a 

 botanist in Southern California. — J. S. Kingsley, American carci- 

 nology in 1879. — A. S. Packard, jun., the structure of the eye of 

 trilobites, with figures ; concludes that the hard parts of the eye of 

 the trilobites and of Limulus are throughout identical, %\hile the 

 nature of. the soft parts of the former must ever remain proble- 

 matical. There is good evidence that the retinal mass was like 

 that of the king-crab ; it so these forms as to their eye-structure 

 will stand near each other and far apart from all other arthro- 

 pods. 



The Journal of the Royal Miavscol-ical Society, June, 

 contains : Prof. Duncan, on a parasitic sponge of the order 

 Calcarea (Plate 10), ■ Mobitisispongia parasitica, growing within 

 Carpcnteria raphidodcndron, from the reefs of Mauritius. — Dr. 

 Cooke, on the genus Ravenelia (Plate 11). — Dr. H. Gibbes, on 

 double and treble staining. An excellent suggestion is incidentally 

 made by Dr. Gibbes, that the covering glasses used by micro- 

 scopists should be of a known thickness. We would even go fur- 

 ther, and advise that a fixed scale of thickness might be adopted. 

 Dr. Gibbes uses two thicknesses, '006 and '004. — Dr. A. 

 Grunow, on some new species of Nitzschia (Plates 12 and 13). — 

 James Smith, on the illumination of objects under the higher 

 powers of the microscope. — The most useful record of cmrent 



