June 25, 1903] 



NATURE 



18s 



Other subjects of exhibits belonging to the physical 

 sciences were : — photographs illustrative of the Coronation 

 Naval Review, 1902, Dr. W. J. S. Lockyer ; the 

 Cooper-Hewitt mercury vapour lamp of the British Westing- 

 house Electric and Manufacturing Company, Ltd., by Prof. 

 Ernest Wilson ; an automatic mercury vacuum pump, by 

 Dr. S. R. .Milner; (i) stereoscopic fluoroscope, (2) stereo- 

 scopic X-ray photographs, Mr. J. Mackenzie Davidson ; 

 detonation of small shells, Dr. O. J. Silberrad ; (i) appar- 

 atus for obtaining monochromatic illumination with the 

 microscope, (2) a new turbidimeter, for determining the 

 turbidity of water, by Mr. Charles Baker ; controlling and 

 regulating spark discharges, experiments in illustration, 

 by Mr. Alfred Williams. 



Prof, E. B. Poulton, F.R.S., illustrated the protective 

 resemblance of butterflies to dead leaves and fragments of 

 dead leaves. \ resemblance to entire dead leaves with mid- 

 rib, traces of oblique veining, and often attacked by fungi, 

 is found in many genera of tropical butterflies. Holes, 

 when represented, appeared to have been gnawed by insects, 

 &c. There are three stages in the representation of such 

 holes : — (i) by opaque strongly reflecting " body colour " ; 

 (2) by transparent windows; (3) by actual apertures. In 

 the Holarctic region, with its deciduous trees, a genus 

 (Polygonia = Giapta) which is defended by the same kind 

 of concealment resembles, not entire leaves, but weather- 

 beaten and ragged fragments, and it is not a gnawed hole 

 which is represented on the butterfly, but a curved crack 

 due to chemical and mechanical changes in a dead leaf 

 fragment. 



The director, Royal Botanic Gardens, Kew, showed three 

 interesting instances of plant adaptations, namely, (i) a 

 sensitive orchid (Masdevallia muscosa) from New Grenada. 

 The lip closes when an insect lights on it ; the insect, in 

 brawling out, is compelled to carry the pollen masses away 

 with it. (2) A case of commensalism (Dischidia rafflcsiana) 

 from Java. Leaves become converted into bags which 

 ants fill with soil ; the plant sends roots into the " flower 

 pots " thus formed. (3) A possible case of protective 

 mimicry (Mesembryanthemum Bohisii) from South Africa. 

 The fleshy leaves simulate the lichen-covered fragments of 

 rock amongst which thev grow. 



An exhibit by Dr. D. H. Scott, F.R.S., and Prof. F. W. 

 Oliver illustrated Lyginodendron and its seed Lagenostoma. 

 Lyginodendron is a characteristic member of the Palaeozoic 

 group Cycadofilices, a group recognised as occupying an 

 intermediate position between ferns and gymnosperms. 

 Hitherto no certain knowledge of the reproductive organs 

 of these plants has been available. A reinvestigation of the 

 detached Coal-measure seeds belonging to Williamson's 

 genus Lagenostoma has furnished evidence which leads to 

 the conclusion that one of them {Lagenostoma Lomaxi) was 

 borne by Lyginodendron. 



Fossil vertebrata from the Fayum, Egypt, were exhibited 

 by the director, British Museum (Natural History). The 

 most important of the specimens were portions of the skull 

 of the remarkable horned mammal, Arsinoitherium, from 

 the Upper Eocene. Specimens of the upoer and lower 

 dentition of the primitive elephants Palaeomastodon and 

 Maeritheriym were also exhibited ; these showed that the 

 teeth are comparatively simple, and that the premolars and 

 molars are in use simultaneously as in the ordinary mammal. 

 Remains of the elephant and antelopes associated with flint 

 implements from the lake beds of the lake Birket-el-Kerun 

 were also shown. 



A chart representing the first results of experiments on the 

 migrations of plaice in the North Sea was shown by the 

 Marine Biological Association. The distances travelled by 

 some of the fishes have been very great, amounting in one 

 casi» to 160 miles in six weeks. The Association also had 

 on view a new British species of the Pblychajte family 

 Sabellaridoe, and living representatives of the Plymouth 

 marine fauna. 



The following were also among the objects on view : — 

 mounted specimen of newly-born Indian elephant {Elephas 

 tnaximus), born in the Zoological Society's Gardens, show- 

 ing the hairy nature of the skin, as in the mammoth, by 

 the director, British Museum (Natural History). A 

 series of spear-heads, manufactured by the existing 

 Aborigines of the north-west territories of Western 

 Australia, by Dr. Henry Woodward, F.R.S. Remains of 



NO. 1756, VOL. 68] 



fossil mammals from an ossiferous cavern of Pliocene age 

 at Doveholes, near Buxton, Derbyshire, by Prof. W. Boyd 

 Dawkins, F.R.S. Colour photographs of living insects to 

 illustrate protective coloration and resemblance, by Mr. F. 

 Knock, (i) Tail feathers from a common male pheasant, 

 illustrating sexual transformation of plumage ; (2) a wild 

 duck bred in captivity showing a converse change, by Mr. 

 S. G. Shattock and Mr. C. G. Seligmann. 



During the evening Prof. E. B. Poulton gave an account 

 of the discoveries of Mr. Guy A. K. Marshall upon the wet 

 season and dry season forms of Rhodesian butterflies. Mr. 

 Marshall has proved, in three cases, by breeding the one 

 from the other, that butterflies which are entirely different 

 in colour, pattern, shape, relation of upper side to under 

 side of wings, and even habits, and the selection of a certain 

 type of country, are only the summer and winter forms of 

 one species. The winter forms are always the better con- 

 cealed in these cases, probably because the butterfly passes 

 a much larger proportion of its life in a state of complete 

 repose. 



The Bioscope Company gave a lantef.i demonstration 

 illustrating the scientific and educational applications of the 

 bioscope. 



THE ENGINEERING CONFERENCE, 



T AST week the Institution of Civil Engineers held the 

 ^^ bi-annual engineering conference for the present 

 year, under the presidency of Mr. John Clarke Hawkshaw, 

 president of the Institution. 



The proceedings commenced on the evening of Tuesday, 

 June 16, when Mr. W. H. Maw, past-president of the Insti- 

 tution of Mechanical Engineers, delivered the eleventh 

 " James Forrest " lecture in the theatre of the Institu- 

 tion, his subject being " Some Unsolved Problems in 

 Engineering." We published an abridgment of Mr. Maw's 

 address last week (p. 163). On the following day, Wednes- 

 day, June 17, the chief business of the meeting commenced, 

 and was continued over the Thursday and Friday following. 

 The conference was divided into seven sections, the members 

 of which met in various rooms near the Institution house 

 in Great George Street. These sections were as follow : — 

 Section i., railways, chairman, Sir Guilford Molesworth ; 

 section ii., harbours, docks and canals, chairman, Sir 

 Leader Williams; section iii., machinery, chairman. Dr. 

 Alex. B. W. Kennedy ; section iv., mining and metallurgrv, 

 chairman, Mr. E. P. Martin ; section v., shipbuilding, 

 chairman. Sir John I. Thornycroft ; section vi., water- 

 works, sewerage and gasworks, chairman. Sir Alexander 

 Binnie ; section vii., applications of electricity, chairman, 

 Mr. Alexander Siemens. 



Before proceeding to the various section rooms, members 

 of the congress assembled in the theatre of the Institution 

 of Mechanical Engineers to hear an introductory address 

 from the president of the Institution of Civil Engineers, 

 Mr. J. C. Hawkshaw. The address alluded to the work 

 done at past conferences, and subsequently referred to the 

 Engineering Standards Committee, which had been 

 organised by the Institution in conjunction with various 

 other technical bodies. The subject of the education and 

 training of engineers was also touched upon, and in con- 

 nection with the Admiralty scheme of training, the presi- 

 dent pointed out that a similar plan of operations was 

 devised by the Institution for the admission of students and 

 associate members. Referring to the pollution of the town 

 by smoke, the president said that " neglect to deal with it 

 is yearly costing the growing population of London a large 

 sum, and a Royal Commission had been appointed to inquire 

 into the subject." The problems of locomotion and trans- 

 port, timber supplies, and motor-car traffic were also dwelt 

 upon briefly. 



Railways. 



The section devoted to railways met on the first and 

 second days of the meeting, five papers being read in all. 

 The first paper was on " The Assimilation of Railwav 

 Practice as Regards Loads on Bridges up to 200 feet Span, ' 

 the subject being introduced by Mr. A. Ross. It was 

 pointed out that it was undesirable to carry standardisation 



