Supplement to '''Nature'' Septefiiber 15, 1923 



421 



Liverpool. He referred to the rapid extension of 

 physiological methods of inquiry to the lower organ- 

 isms, the discovery of artificial parthenogenesis, the 

 intensive study of egg-cleavage, cell-lineage, and the 

 maturation of the egg and sperm, the remarkable 

 )rogress of cytology, and to researches on the structural 

 )asis of heredity and on the nuclear mechanism 

 jrrelated with sex. Other subjects discussed were the 

 [study of the finer structure of the nerve-cell and its 

 processes and of the neuromotor system of the Protozoa, 

 the investigations on the ciliate Protozoa, especially on 

 Paramsecium, with the purpose of ascertaining whether 

 decline and death depend on inherent factors or on ex- 

 ternal conditions, and the researches on the culture of 

 tissues, which are leading to a knowledge of the con- 

 ditions which determine the growth and differentiation 

 of somatic cells. 



In the second part of the address some of the bear- 

 ings of zoology on human welfare were considered. 

 At the time of the last meeting in Liverpool insects 

 were suspected of acting as transmitters of certain 

 pathogenic organisms to man, but these cases were 

 few and in no single instance had the life-cycle of the 

 organism been worked out and the mode of trans- 

 mission from insect to man ascertained. The part 

 played by the mosquito as host and transmitter of 

 the parasite of malaria was made known by Ross 

 nearly two years after that meeting. Of the ten 

 important examples of arthropods now proved to act 

 as carriers of pathogenic organisms to man, Prof. 

 Ashworth chose three for consideration, namely, 

 Stegomyia and yellow fever, tsetse-flies and sleeping- 

 sickness, and the flea Xenopsylla cheopis and plague, 

 this last providing a fine illustration of the value of 

 careful work on the systematics and on the structure 

 and bionomics of the insect concerned. Intensive 

 work on the Protozoa has been an outstanding feature 

 during the last twenty-five years, and Entamoeba 

 histolytica, the organism of amoebic dysentery, was 

 taken as an example of the importance of researches 

 on Protozoa which directly affect man. Of the notable 

 investigations on parasitic worms, reference was made 

 to the great advances in our knowledge of the life- 

 history and bionomics of Ancylostoma and of Schisto- 

 soma (Bilharzia), which have enabled effective measures 

 to be taken against infection by these parasites. 



In conclusion, Prof. Ashworth referred to the place 

 and value of zoology in the medical curriculum, gave 

 an outline of the subjects which he considered should 

 be included in the course of zoology for medical 

 students, and invited discussion on this part of the 

 address. 



The British Empire as a Maritime State. 



The subject of Dr. Vaughan Cornish's presidential 

 address to Section E (Geography) is the " Geo- 

 graphical Position of the British Empire." It may be 

 thought that an Empire on which the sun never sets, 

 with lands in both hemispheres and on every continent, 

 cannot be assigned a place upon the map, and in fact 

 so long as it is regarded from the continental point of 

 view it cannot be given a definite geographical position. 

 It is, however, a maritime State, the metropolitan and 

 other provinces being united by ocean routes on which 



lie British ports of call which can be used as naval 

 stations, but separated strategically by those parts 

 of the ocean which are not so provided, and are readily 

 dominated from the ports of other Great Powers. An 

 examination of these conditions shows that, taking 

 account only of the communications which are avail- 

 able in all circumstances, the lands of the British 

 Empire are connected by the Atlantic and Indian, 

 separated by the North Pacific Ocean. Hence the 

 geographical position of the Empire is well represented 

 by the form of Mercator map in which the meridian 

 of Greenwich is central and the right- and left-hand 

 edges are at longitude 180°. The Empire thus 

 appears astride the North Atlantic and the Indian 

 Ocean, but with its Pacific shores unconnected. 



A symmetrical arrangement is revealed upon this 

 map if a direct line (part of a great circle) be drawn 

 from Halifax, Nova Scotia, the eastern terminal of the 

 Canadian Pacific Railway, to Fremantle, the western 

 terminal port of the Australian railways. This direct 

 line (twisted on the map into the form of the letter S) 

 passes through Lower Egypt close to the Suez Canal, 

 which is not very far from its middle point. It follows 

 somewhat closely the main steamship track of the 

 Empire. At one end is Canada, at the other Australasia, 

 the British Isles on the north and South Africa on the 

 south. The coloured populations of the Empire are 

 also distributed symmetrically with reference to the 

 line, those of India on the east, of Africa on the west, 

 so that the great circle from Halifax, N.S., eastwards 

 to Fremantle is the geometrical axis of the Empire. 



The Empire as thus mapped can be shown to have 

 an intermediate position on the present commercial 

 and international communications of the world such 

 as no other Great Power occupies, so that the British, 

 in a greater degree than any other people, are the 

 doorkeepers of the world. 



The consolidation of the position turns on the future 

 of colonisation during the time which remains before 

 the untilled lands of the world are occupied by peasantry. 

 In the second part of the address the present tendency 

 of this movement is traced both among coloured and 

 white peoples, and special attention is given to the 

 question, now so much debated, whether a surplus of 

 birth-rate over death-rate in Great Britain is, or is 

 not, in the interests of the country, of the peoples of 

 the Empire, and of mankind. 



Population and Unemployment. 



The common impression that Europe is already 

 threatened with over - population may be traced 

 to two sources — to observation of the exceptional 

 volume of unemployment to-day, and to the words of 

 certain economists describing Europe before the War. 

 Sir William Bevcridge deals with these subjects in his 

 presidential address to be given to Section F (Economics) 

 on Monday, September 17. Unemployment does not 

 necessarily or naturally point to excessive growth of 

 population ; severe and prolonged unemployment has 

 occurred at times and in countries which were certainly 

 not marked by over-population. Statements such as 

 those of Mr. Keynes, that Europe was over-populated 

 even before the War, appear ill-founded ; in Europe, 

 no less than in the New World, the yield of com 



