590 



NA TURE 



[October i i, 1900 



structure, formation and growth of the coral reefs of the Indian 

 Ocean. Special attention was given to the island of Minikoi, 

 in the Laccadive group. It was clear from their observations 

 that in this atoll there had been an elevation of the original 

 reefs to a height of at least 25 feet above low tide level. All 

 their evidence showed that the lagoons of atolls were generally 

 formed by the solution of the central rock of originally more or 

 less fiat reefs. 



Prof. R. Burckhardt followed with a paper on the anatomy 

 and systematic position of the Lcemargidae. He recorded the 

 discovery of luminous organs in nine species of Laemargidre 

 and Spinacidns. The affinity of these families of sharks was 

 further evidenced by his discovery of a cartilage hook in the 

 dorsal fins of Laemargtis. 



Prof. Burckhardt also showed photographs and other illus- 

 trations of the nestling kagu (Ehinochetus), a rare flightless bird 

 of New Caledonia. 



Prof. R. J. Anderson described the dentition of the seal ; and 

 Mr. Graham Kerr, on behalf of Mr. G. E. H. Barrett-Hamilton, 

 exhibited some skulls of Antarctic seals (chiefly Phocidoe) brought 

 home by the Belgian expedition. 



On Tuesday, Mr. N. Annandale exhibited a number of photo- 

 graphic slides illustrating the appearance and habits of some 

 Malay insects under natural conditions. One striking series 

 represented the pupa of a Mantis {Hymenopus bicorjtts) seated on 

 an inflorescence of the so-called '"Straits Rhododendron" 

 (Melastoma polyanthuin), a detailed resemblance to which is 

 brought about by the colour and shape of the insect, and by the 

 extraordinary attitude which it adopts upon the flower. 



Prof. E. B. Poulton also showed a large number of slides, 

 representing the collections of insects made by Mr. G. A. K. 

 Marshall in Mashonaland and Mr. R. Shelford in Borneo, as 

 arranged in the Oxford Museum to illustrate the general prin- 

 ciples of Miillerian mimiciy. An interesting series of mutilated 

 butterflies caught at large showed the comparative rarity of in- 

 discriminate injuries by birds, and the frequency with which 

 enemies aimed at the conspicuously marked tips of the fore- 

 wings and at the back of the hind-wings, where tail-like pro- 

 cesses were so commonly developed, these being just the places 

 where the bites would be least dangerous to the insects. 



Other slides, illustrating mimicry and protective resemblance, 

 were exhibited by Mr. Mark L. Sykes ; and Prof. Lloyd Morgan 

 described some recent experiments upon newly-hatched chicks, 

 which showed that the avoidance of distasteful forms by birds is 

 not instinctive, but the fruit of experience. Chicks fed for a 

 time on palatable food placed on black-and-orange banded slips 

 of glass did not hesitate to attack the distasteful caterpillars of 

 the cinnabar moth when these were eventually oH"ered them ; 

 whereas chicks which had been accustomed to associate the same 

 col.iured slips with bad food refused to attack the similarly 

 striped caterpillars. These observations provided a sound 

 experimental basis for the Miillerian theory of mimicry. 



Mr. F. W. Gamble described the results of investigations 

 made by Mr. F. W. Keeble and himself on the colour changes 

 of various prawns, especially Hippolyte varians, his paper being 

 illustrated by a series of living specimens as well as by lantern 

 slides. The prawns adapted their colours to those of surround- 

 ing weeds ; but, whatever their colour during the day, they 

 always assumed a characteristic blue colour at night. This 

 change, in newly-caught specimens, came on at the proper time 

 quite independently of the darkness, and the morning phase 

 would be resumed at daybreak, even when the animal was kept 

 in the dark. After a few days under such unnatural conditions, 

 however, the periodicity became altered. 



A paper, by Dr. ^Eneas Munro, on the locust plague and its 

 suppression concluded the business of the section. 



GEOGRAPHY AT THE BRITISH 

 ASSOCIATION. 

 'T'HE work in Section E at the Bradford meeting was some- 

 what limited in amount, but its quality was in no way 

 below the average. In fact, the number of " popular " papers 

 was smaller than usual, while those of a more serious character 

 predominated. The section was excellently housed in the 

 Church Institute, and the meeting began with a presidential 

 address of quite a novel character. Sir George Robertson' took 

 the British Empire as his text, and laid great stress on the 

 relative shrinkage of distances by the improvement of means of 

 communication by land and sea, a fact which in great measure 



NO. 1615. VOL. 62] 



neutralised such ill effects as might arise from continuous 

 expansion of territory. 



The keynote struck by the president was geography as the 

 science of distances, and in unison with it a series of papers 

 dealt with problems of which distances and means of transport 

 were the essential features. Mr. E. G. Ravenstein discussed 

 the question of foreign and colonial surveys in a comprehensive 

 paper, in which he pointed out the manner and extent of the 

 official surveys of the chief countries of the world. While recog- 

 nising that the British Ordnance Survey fell short of perfection, 

 he considered that its accuracy was not equalled by the maps of 

 any other country. He strongly urged the adoption of a more 

 systematic method of surveying in Africa, in many parts of which 

 the only existing maps were produced by travellers with in- 

 adequate assistance and many other things to do. In comment- 

 ing on the paper. Colonel Johnston, the Director-General of the 

 Ordnance Survey, explained the position of South Africa with 

 regard to its surveys. He said that a nearly perfect system of 

 triangulation had been carried out, but this has not yet been 

 utilised by being made the foundation of a detailed survey. 



Mr. B. V. Darbishire read a paper on military maps, with 

 special reference to the use of the Ordnance Survey Maps in field 

 manoeuvres. 



Colonel Sir Thomas II. Holdich discussed the question of a 

 railway connection between Europe and India. He considered 

 the northern approaches to India across Kashmir or the Hindu 

 Kush from the Oxus valley to be impracticable. On the other 

 hand there appeared to be no insurmountable difficulty in the way 

 of a connection by the Hari-rud valley, through which approach 

 a distance of only 500 miles intervened between the farthest out- 

 posts of the existing railways, Kushk on the Russian side and 

 New Chaman on the Indian. The new line would pass by 

 Kandahar. This line could, in the opinion of the author, be 

 made to pay by local traffic, and he believed it would strengthen 

 rather than weaken the defences of India. 



Mr. C. Raymond Beazley read a paper, which was largely 

 historical and statistical, on the Trans-Siberian railway. 



Mr. G. G. Chisholm gave a very timely forecast of the prob- 

 able economic changes which may be expected to result from the 

 imminent development of the resources of China by modern 

 methods. These would include, in his opinion :— A rise in 

 prices in China, especially in the industrial regions ; a demand 

 for food-stuffs not likely to be supplied by China itself; a great 

 stimulus to the food-producing regions most favourably situated 

 for meeting this demand, more particularly Manchuria, Siberia, 

 and western North America ; and the creation of a tendency to 

 a gradual but prolonged rise in wheat and other grain prices all 

 the world over, reversing the process that has been going on 

 since about 1870. 



Mr. Edward Heawood treated of the commercial resources of 

 tropical Africa, and his paper also partook of the spirit of fore- 

 cast, his expectations being that Africa will greatly increase in 

 importance by the cultivation of tropical plantations. 



The travel papers which excited the most interest were those 

 contributed by Mr. Borchgrevink on his expedition to the 

 Antarctic regions and by Captain II. H. P. Deasy on his journeys 

 in Central Asia. Both were illustrated by remaikably fine lan- 

 tern slides. As the facts which they recounted have already 

 been published, it is unnecessary to summarise them here. 



Physical geography occupied a large part of the time of the 

 section, and, with regard to this part of the work, it is impossible 

 to refrain from expressing the desire that some arrangement 

 might be come to with regard to the section in which papers 

 lying on the borderland between different subject? should be 

 treated. With regard to meteorology, for instance, might it 

 not be arranged to read all climalological papers — the essential 

 principle of which is geographical distribution — at Section E, 

 and only the theoretical papers or those dealing with instruments 

 and atmospheric physics at Section A ? 



On this occasion the report of the committee on the climate 

 of tropical Africa, of which Mr. H. N. Dickson is secretary, 

 was read to Section E, and a remarkable discussion of the 

 geographical distributions of relative hupidity was presented 

 by Mr. E. G. Ravenstein to the same section. In this he 

 said that, notwithstanding the paucity of available material, 

 he had ventured, in 1894, to publish in Philip's " System- 

 atic Atlas," a small chart of the world showing the distri- 

 bution of humidity, and he now placed the results before this 

 meeting with some diffidence. His charts brought out the 

 broad leatures of the subject, and to reduce the sources of error 



