98 



NATURE 



[October 2, 1919 



and mice, more or less harmless to domestic animals. 

 The destructive power of virus was found to be more 

 untrustworthy than that of some poisons. The most suc- 

 cessful' form of trap consists of a tunnel-shaped cage 

 with open doors at each end, which shut when the 

 rat treads on a platform in the centre of the passage. 

 The common steel gin-trap was specially successful 

 when covered with wire tunnels. .\ large number of 

 experiments were conducted in order to ascertain 

 whether there w-as any truth in the statement that 

 rats are influenced by human odour. As a result cf 

 these experiments it was found that it was superfluous 

 to avoid handling traps on the assumption that rats 

 are detracted by the odour of man. Sulphur dioxide 

 was found to be the most effective gas, and was 

 recommended for killing rats on ships and in con- 

 fined spaces. When driven off under pressure, the 

 gas could be used with success in fumigating rat- 

 holes in the open. Details of the research will be 

 found in a "Report on Methods of Rat Destruction," 

 by Mr. E. G. IJoulenger, shortly to be published by 

 the Zoological Society, price 6d. 



The Proceedings of the United States National 

 Museum (vol. Ivi., No. 2288) contains an interesting 

 paper entitled "Descriptions of New Species of Mol- 

 luscs of the Family Turritidae from the West Coast 

 of America and Adjacent Regions " by Dr. W. H. 

 Dall. In all, somewhat more than 200 species are 

 considered, of which 181 are new. Of this large 

 number 93 belong to the fauna of the western coast 

 of the United States from the Arctic Ocean to San 

 Diego, California, including one species from Hawaii. 

 Eleven species appertain to the west coast of South 

 America, including the Galapagos Islands ; 89 belong 

 to the Panamic fauna and its extension into the Gulf 

 of California. The new species are well figured on 

 twenty-four plates reproduced from excellent micro- 

 photographs. 



During the early days of rubber-planting, seed was 

 put in regardless of its origin, whether from trees 

 yielding large or from trees yielding small quantities 

 of latex. Now, however, so much rubber is planted 

 that there is danger of over-production, and for 

 further plantations (now that capital costs have 

 increased) to have much chance of success they 

 should be planted with seed from the best bearers. 

 Selection of seed is already in progress in Ceylon and 

 elsewhere, and a paper by Whitby ("Variation in 

 Hevea. brasilietutis," Ann. of Bot., vol. xxxiii., 1919, 

 P- 313) provides useful data which give an idea of the 

 possibilities of improvement in average yield. A large 

 number of trees were tapped on a uniform system 

 (in Malaya), and it was found that nearly 10 per cent, 

 vielded twice the mean or more. If, then, the method 

 of selection indicated in Lock's " Rubber and Rubber- 

 Planting " (p. loi) were adopted, there seems good 

 reason to hope that new plantations might be made 

 yielding much more rubber per acre than the old. 



The possibilities of camphor cultivation in the West 

 Indies has recentlv been discussed in the Agricultural 

 News for May 31 last. The decreasing amount of 

 camphor available for export from Japan, which has 

 hitherto been the main source of supply, has led to 

 experimental growth of the camphor-tree in various 

 West Indian Islands. It has been found that some 

 varieties of the tree yield oil only, while others yield 

 camphor and oil, and this important botanical aspect 

 of the question is being investigated at Kew. With 

 the right variety, the leaves and twigs, as well as 

 the wood and roots, are found to yield camphor on 

 distillation, and the trees will bear severe pruning 

 with little apparent injury. Camphor production 

 appears to be an industry which might profitably be 

 NO. 2605, VOL. 104] 



developed in several West Indian islands, where 

 climatic and soil conditions are suitable ; for instance, 

 Jamaica, Trinidad, Dominica, and others. Camphor 

 hedges as wind-breaks to lime or cacao plantations 

 might be experimented with, even if extensive area.s 

 were not devoted entirely to camphor plantations. 



Among recent publications of the Board of -Agri- 

 culture is the first annual report of the Flax Produc- 

 tion Branch — a branch formed in 1917 to arrange for 

 the growth of at least 10,000 acres of flax in Great 

 Britain. It is estimated that the 1918 crop will yield 

 about 26,500 tons of straw and seed. The cost of 

 production has been enormous, chiefly owing to the 

 great difficulty in obtaining the large amount of 

 labour necessary for harv'esting the crop. Pre-war 

 experiment stations proved the possibility of flax pro- 

 duction on a small scale in Great Britain, but it would 

 be obviously unfair to take last year's experience as a 

 guide to the possibility of a large-scale flax industry. 

 The latter will depend on foreign imports and prices, 

 on the development of flax-growing in other countries, 

 and also on the hitherto unattacked problem of the 

 reduction of costs in all the stages of production. Im- 

 provements already in sight are the increased straw 

 yield from selected strains, and the progress made 

 with the threshing attachment which makes de- 

 seeding on the farm possible. Also, it must be re- 

 membered that, failing the large-scale establishment 

 of the flax industry, considerable loss will be sustained 

 in the disposal of the machinery which has been put 

 up during the past vear. 



The recently issued volume of the Journal of the 

 Royal Agricultural Society (vol. Ixxix., 1918) contains 

 several papers of great interest in connection with the 

 food production campaign carried on during the war. 

 Prof. Bryner Jones describes the results of breaking 

 up grass-land in 1918. This will always rank as 

 one of the most remarkable achievements of British 

 agriculture, contributing as it did so largely to the- 

 food-supply of the country in times of great need. 

 It was fitting, therefore, that the technical problems 

 should be recorded and discussed. Teachers and 

 experts will hope that an even fuller account may be 

 published eventually, giving details of soil formations 

 and conditions that will add to its usefulness. Mr. 

 Garrad describes the work of the tractor on the farrn. 

 This implement is rapidly revolutionising farm condi- 

 tions, and is greatly increasing the efficiency of th<! 

 farm-worker. The defects of present types are set oui; 

 and suggestions made for the consideration of en- 

 gineers. Unfortunately, the great enemy of the 

 tractor is the weather; in Mr. Garrad's opinion, it is 

 essentially a fine-weather machine, and has to be laid 

 up in wiriter. But it works so quickly that it enables 

 a farmer to do much of his work during the fine 

 periods. Mr. J. R. Bond gives an account of modern 

 haymaking machinery, and Mr. .Arthur .Amos discusses 

 the difficulties of growing red clover. 



The Rev. M. Saderra Mas6, who has studied the 

 seismic and volcanic phenomena of the Philippine 

 Islands for many years, has recently published the 

 catalogue of earthquakes for the year 1918 (U.S. 

 Weather Bulletin for December, 1918). Excluding 

 after-shocks, the total number of earthquakes is 167, 

 three of which were recorded all over the world. 

 The most important earthquake was that which 

 occurred in Southern Mindanao on .August 15 at 

 12.20 p.m.. G.M.T., its epicentre being in 55° N. lat. 

 and 124-5° I^- 'o"S- This shock, the intensity of 

 which reached the highest degree (10) of the Rossi- 

 Forel scale, was followed by thousands of after- 

 shocks (some of them of degrees 7 and 8) during the 

 months of August, September, and October. It was 



