490 



NATURE 



[August 22, 19 18 



tion later spread to the American race. The disease 

 manifests itself in the caterpillars, which suffer from 

 diarrhoea, cease to eat, lose muscular co-ordination, 

 and die. The microbe is a streptococcus and is con- 

 veyed by ingestion, and the muscular tissue of the 

 insect is first attacked. The disease was introduced 

 into woods heavily infested with the gipsy moth, and 

 in two localities severe epidemics were produced. It 

 is hoped that it may be of service in helping to combat 

 the ravages of the gipsy moth. In another paper in the 

 same journal Mr. J. Rosenbaum discusses the survival 

 of the blackleg organism of the potato in the soil 

 during winter. The or.ganism (Bacillus phytophthorus) 

 does not seem to be able to survive in the soil or in 

 diseased tubers that may remain there under winter 

 conditions. 



The Kew Bulletin, we are glad to notice, is being 

 published this year with regularity, and five numbers 

 have already appeared. In No. 5 there is a valuable 

 article on the preservation of wood by the application 

 of chemicals, which plays so important a part in 

 timber economy. The chief value of preservatives is 

 to render the wood less susceptible to the attacks of 

 parasitic fungi, to make it waterproof and less in- 

 flammable, and to prevent the attacks of boring 

 insects. Ac general account of the subject is given, 

 and then attention is directed in detail to the im- 

 portant book on the subject recently published by 

 Mr. A. J. Wallis-Tayler. The various chapters of 

 the book are reviewed, and this is followed by a 

 bibliography of works upon other definite branches 

 of wood preservation, such as wood pavement, 

 creosoting railway sleepers, etc. A number of the 

 works cited have been published in the United States 

 and some from India, while others dealing with the 

 treatment of timber for estate purposes have been 

 published in the Quarterly Journal of Forestry. 



The Journal of the Royal Agricultural Society 

 (vol. Ixxviii.) contains two papers relating to milk 

 production and distribution which are of interest to a 

 far wider circle of readers than the members of the 

 society. Mr. James Mackintosh, adviser in dairying 

 to University College, Reading, discusses the effect 

 of the new agricultural policy, on the dairy-farming 

 industry. The increase in arable area at the expense 

 of the grass area is thought by many dairy-farmers to 

 necessitate a reduction of herds, but although Mr. 

 Mackintosh declines to accept this conclusion, and 

 offers evidence that more food for cows can be pro- 

 duced when a certain amount of grassland is broken 

 up, he anticipates that the higher cost of production 

 and the greater labour involved in arable dairying as 

 contrasted with other systems of farming, which may 

 in the future be equally remunerative, may lead to a 

 decline in milk-production in districts best adapted for 

 corn-growing, such as the Eastern Counties, and hence 

 possibly to diflficulties of supply in these areas. In the 

 West a decline is less to be feared if the prices of milk 

 and milk products allow of reasonable profit, and 

 adequate means of education are provided. In a paper 

 on the wastage of milk Dr. R. Stenhouse Williams 

 gives some striking figures as to the extent to which 

 milk is at present lost by souring, splashing, and in 

 other ways, ana indicates the lines along which a 

 rational system of production and distribution of clean 

 milk might be organised. 



The unknown Belcher Islands, in the south-east of 

 Hudson Bay, were explored in 1914 and 1915 by Mr. 

 R. J. Flaherty, who for the last six years has been 

 examining the Hudson Bay region, the Ungava Penin- 

 sula, and Baffin Land for iron-ore and other mineral 

 deposits. Mr. Flaherty has an article on the islands 

 NO. 2547, VOL. lOl] 



in the June number of the Geographical Review 

 (vol. v., No. 6). The article contains several illustra- 

 tions and the first map of the islands to be published. 

 Previously they were represented on charts by dotted 

 outlines of incorrect shape and position. It appears 

 that the Belcher Islands consist of several long, narrow 

 islands extending north and south for ninety-one miles, 

 with an extreme width of fifty-seven miles. Their area 

 is more than 5000 square miles. The islands are low, 

 rising barely to 500 ft. at most, and studded with 

 lakes well supplied with salmon and other fish. Har- 

 bours are numerous. Vegetation is scanty, and there 

 are no trees, but animal life is abundant. A tribe of 

 Eskimos, consisting of only five families, permanently 

 inhabit the islands. Other Eskimo - from time 

 to time migrate from the mainland in search of 

 walrus, sea-fowl, and, before their disappearance, 

 caribou. Mr. Flaherty reports large deposits of iron- 

 ore, not, however, of high quality. It is remarkable 

 that such a large and not unimportant group of 

 islands, comparatively near to civilisation and easy of 

 access, should have remained so long unexplored. 



Kisskalt's view that the action of the sand filter 

 in water purification is biological and due to the 

 destruction of bacteria by other organisms is contested 

 as the result of experience at the Zurich waterworks, 

 where the lake-water is filtered in two stages through 

 sand. According to L. Minder (Journal fiir Gas- 

 beleuchtung und Wasserversorgung, No. 61, 1918), 

 the first layer retains most of the fresh-water plank- 

 tons, but allows some of the bacteria to pass. The 

 bacteria are retained by the second filter and at the 

 surface, so that at a depth of 10 cm. the number per 

 cubic centimetre has already fallen to one-tenth. 

 Furthermore, the retention of bacteria is satisfactory 

 even when there are considerable fluctuations in the 

 number of bacteria in the water. Thus it is concluded 

 that the process is mechanical rather than biological. 



According to the Annali d'Ingegneria e d'Archi- 

 tettura for June 16, a strong committee of business 

 men has been formed to consider the possibility of con- 

 structing, after the war, a canal connecting Milan with 

 Lake Como, and joining the important wateiway 

 which it is proposed to make from Milan to Venice, 

 thus opening up the rich plains of Lombardy to cheap 

 means of transit. The works involved would com- 

 prise a canal from Milan to Vimercate, a vast tunnel 

 from Vimercate to the River Adda, and the canalisa- 

 tion of the Adda from Paderno to Lecco. The scheme 

 has the approval of the city of Milan, and will be 

 supported bv the Edison Company, which is the chief 

 user of the waters of the Adda. Some of the features 

 of the new undertaking are discussed, and the advan- 

 tages which the new canal would confer on Milan are 

 explained. The distance -by water from Milan to 

 Lake Como would be reduced by about eleven miles. 



In a paper on the limit of sensibility of the eye 

 and the minimum of power visually perceptible, which 

 appears in the March-April issue of the Journal 

 de Physique, M. Buisson claims that the eye is much 

 more sensitive than it has been thought to be. _ A 

 number of discs of diameters from 2-5 to 5 milli- 

 metres were covered with phosphorescent material, and 

 the light sent out by them determined by the Fabry- 

 Buisson micro-photometer to be between two and four 

 candles per square centimetre. Two of these discs of 

 the same size and strength were mounted on a screen, 

 which was gradually removed from the observer and 

 at the same time rotated about his line ofsight,^ and 

 he was required to state the direction the line Joining 

 the two discs made with the horizontal until with 

 increase of distance it became impossible. For discs 



