i6o 



SCIENCE- GOSSIP. 



Double Fertilisation in Zea Mais. — M. L. 

 Guignard ("Journ. du Bofcanique," 15, pp. 1-14, 

 1901) finds in Zea Mais the same phenomenon as 

 has recently been discovered in many other 

 Angiosperms, chiefly however Dicotyledons. The 

 mature pollen-grain in Zea presents, besides the 

 vegetative nucleus, two generative nuclei. In the 

 embi-yo sac the polar nuclei do not fuse before 

 fertilisation, and at the antipodal end of the sac 

 are as many as twelve multi-nucleate cells. This 

 is, perhaps, remarkable. One of the male cells 

 unites with the oosphere, and one with the polar 

 nuclei, which latter are bound together by the last 

 male cell. A similar phenomenon occurs in Tiilipa 

 gesneriana, vide ante, p. 127. 



Leaf of Ginkgo Biloba. — It is interesting to 

 notice the points in which the leaf of Ginkgo (Sub- 

 order Taxineae, Ord. Coniferae) differs in structure 

 from that of the yew or Pinus. On microscopical 

 examination the transverse section across the leaf, 

 with its numerous palmately arranged bundles, 

 presents many of the usual features, a number of 

 relatively enormous resin-canals being disposed one 

 between each two of the bundles. The epidermal 

 cells are very large, but there is no hypodermis 

 (Pinus and Taxus have well-marked hypodermis); 

 the mesophyll cells are arranged and have the same 

 shape as those of Taxus, and are densely crowded 

 with chloroplasts. The bundles also show the 

 distinctive features of those of a Conifer ; the 

 central cylinder being enclosed by a number of 

 large, thick-walled sclerenchymatous elements, on 

 the walls of some of which reticulations can be 

 seen. The xylem and phloem are well marked, the 

 former being uppermost. On the whole, the internal 

 structure of the leaf of Ginkgo, as far as concerns 

 the relative arrangement of the various tissues and 

 the centric type of the fibro-vascular bundles, shows 

 a distinct relation to other Coniferae. The absence 

 of hypodermis is not an important point, except 

 with regard to protection and rigidity. The shape 

 of the leaf is certainly peculiar, being broad, 

 bilobed, and with a palmate venation. The number 

 of bundles being very great, each leaf arises singly. 

 From the form of its leaf Ginkgo might be an 

 Angiosperm. Should this leaf be called " bifacial " 

 or "centric" 1 We can divide the whole structure 

 into smaller portions, each containing two resin- 

 canals and one bundle, and each of these is centric 

 in itself. Does this fact, however, make the whole 

 leaf centric ? 



NOTICES OF SOCIETIES. 



Ordinary meetings are marked t, excursions * ; names of persons 

 following excursions are of Conductors. Lantern Illustra- 

 tions §. 



South London Natural History Society. 



Oct. 5. — * Fungus Foray to Oxshott. W. J. Lucas and E. Step. 



Nov. 28. — t Annual Special Exhibition. 



Jan, 23. — Annual General Meeting. 



Yorkshire Naturalists' Union. 

 Oct. 17. — Annual Meeting. 



Birkbeck Natural History Society. 



Oct. 12.—* Forest Gate for Wanstead Park. E. H. Potts, B.A.. 

 „ 12.— f Lecture. Miss E. M. Thomas. 



Nottingham Natural Science Rambling Clur. 

 Oct. 26. — Annual Meeting. 



North London Natural History Society. 



Oct. 8. — f " Notes on the Colour o£ Birds' Eggs." S. Austin. 



„ 12. — * Kew Gardens. 



„ 22. — " Colour in Nature." W. Mark Webb. 



Hami'stead Scientific Society. 



Oct. 5. — * Museum, lloyal College o£ Surgeons Lincoln's Inn 

 Fields. 



NOTICES TO CORRESPONDENTS. 



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ANSWERS TO CORRESPONDENTS. 



G. H. E. (Bracknell). — There is an article upon the subject of 

 drying plants in the last number of Science-Gossip. Perhaps 

 the writer might give you further aid on application. 



W. H. H. (Cardiff). — We will hand your letter to a dipterist, 

 who will doubtless give you the assistance you require. 



EXCHANGES. 



Notice. — Exchanges extending to thirty words (including 

 name and address) admitted free ; but additional words must be 

 prepaid at the rate of threepence for every seven words or less. 



Micro Material. — Wanted; fresli pollens, starches, di toms, 

 zoophytes, Coleoptera (good British or foreign), also sponge 

 spicules or other interesting marine specimens. Must be cor- 

 rectly named. Send list and quantity. Liberal exchange given 

 in either other material, mounted specimens, or microscopic 

 apparatus. — R. Mason, 69 Park Road, Clapham, London, S.W. 



Roscoe's " Chemistry," latest edition, quite new ; also 

 " Story of Chemical Elements" Wanted; Mill's "Logic," in 

 good condition.— Edward R. Swales, Clifton Villa, Sandbach, 

 Cheshire. 



Owls' Eggs, three — Exchange for hawks' or other birds' 

 eggs. — A. Hall, Mantle Road, Leicester. 



Hesperia lineola. This year's, unset. Wanted, local 

 butterflies. — W. R. Hayward, Sawbridgeworth, Herts. 



Minerals, including some American specimens, and fossils, 

 offered in exchange for shells. — H. W. Parritt, 8 Whitehall 

 Park, N. 



Pathological Sections, 20 good and different, what offers ? 

 Wanted ; Halliburton's " Chemical Physiology," or a text-book 

 of internal insect anatomy. — J. T. Holder, 77 Erlanger Road, 

 St. Catherine's Park, S.E. 



CONTENTS. 



page 



Scenery of Llanberis Pass. By E. E. Filer. Illus- 

 trated ' 129 



The Soil and the Plant. By Dr. P. Q. Keegan . . 131 



Notes on Rottfera. By Walter Wescue . . . . 133 

 The Chemistry of Chromate Printing. By Lewis 



Ough, F.C.S .. ..135 



Notes on SpjNNing Animals. By H. Wallis Kew .. 137 

 An Introduction to British Spiders. By Frank 



Percy Smith .. ..138 



The Structure of Plants : a Chapter in Organic 



Evolution. By Rudolf Beer 140 



Books to Read. Illustrated ..141 



Science Gossip 144 



In Memoriam. Illustrated 147 



Notes and Queries. Illustrated 148 



Photography. .. 150 



Chemistry 151 



Physics 152 



Microscopy. Illustrated 153 



Astronomy 157 



Botany. Illustrated 158 



Notices— Exchanges 160 



