326 



NATURE 



[June 26, 19 19 



in reducing Tyroglyphid pests. It is found that 

 mites will not injure wheat and flour in which the 

 moisture content is 1 1 per cent, or less, whatever 

 the temperature may be. When the moisture 

 exceeds 13 per cent, they increase and flourish ex- 

 ceedingly ; given favourable moisture conditions, 

 the mites increase very rapidly between 60° and 

 75° F., while between 40° and 50° F. increase is 

 retarded. The remedy advised for mite-infested 

 wheat is to screen it thoroughly in order to re- 

 move as many of the mites as possible, and to 

 subject it to treatment whereby the moisture is 

 reduced, such as a blast of hot air followed by 

 cooling. Prevention from attack may be secured 

 by storing flour with a low moisture content — 

 below 1 1 per cent. The lowest lethal temperature 

 for the mites was found to be 120° F., which 

 required at least six hours' application to be effec- 

 tive. In the form of appendices to the report are 

 observations by Prof. Beattie on the degeneration 

 of flour caused by bacteria, and by Mr. A. E. Hum- 

 phries on an examination of flour samples into 

 which acari had been introduced. 



In the third report Prof. Dendy, in conjunction 

 with Mr. H. D. Elkington, records the effect of 

 air-tight storage upon other grain insects. It is 

 claimed that air-tight storage is probably the most 

 effective method of preserving all grain and cereal 

 products from any insect or mite attack. It is 

 particularly satisfactory to note that this method 

 was found to be successful in destroying the larvae 

 of the notorious Mediterranean flour moth 

 (Ephestia kuhniella), along with the various other 

 species dealt with. At the end of the report 

 Prof. Dendy gives an account of experiments 

 which go a long way towards proving that the 

 beetles Triholium castaneum and Silvanus surina- 

 niensis are unable to attack sound wheat. It 

 appears, therefore, that these pests are of a 

 secondary nature, only attacking and completing 

 the destruction of already damaged grain. In a 

 third article Prof. Dendy records observations 

 which confirm the general opinion that Calandra 

 oryzae and C. granaria are powerfully attracted by 

 moisture. When water is present in sufficient 

 quantity, C. oryzae is the more strongly attracted 

 species. 



In the forthcoming reports we shall look forward 

 to a presentation of the results of testing these 

 important laboratory experiments on a large scale 

 in mills, warehouses, and elsewhere. During these 

 times of food scarcity and high prices it is urgent 

 that opportunities for this work should be afforded 

 as speedily as possible. Every saving in grain 

 destruction, with the consequent economy in the 

 use of shipping, contributes towards the early 

 settling down of the country to more normal con- 

 ditions. To avoid waste in every form should be 

 a keynote of natior;il reconstruction. The import- 

 ance of storage in air-tight receptacles is widely 

 recognised in India, although the factors involved 

 have not been understood. The initial difficulties 

 of constructing air-tight silos and receptacles need 

 to be surmounted. Once this is achieved, as 

 Prof. Dendy remarks, the method is likely to 

 NO. 2591, VOL. 103] 



prove valuable where large quantities of grain 

 have to be stored for lengthy periods, especially 

 in hot climates or even during long sea voyages. 

 Air-tight storage is likely to prove effective not 

 only as a preventive measure, but also as a remedy 

 against badly weevilled grain. Both the Commit- 

 tee and the investigators directly concerned are 

 to be congratulated upon the experimental results 

 so far achieved. Fundamental observations of 

 this nature can scarcely fail to prove beneficial to 

 the State. A. D. Imms. 



THE JEWELRY TRADE IN WAR-TIME.^ 



MINERAL INDUSTRY" is an annual 

 publication which treats of the state of 

 the trade of the various minerals entering into 

 commercial use in the United States during the 

 previous year. The volume for the year 1917 did 

 not appear until the close of last year. As for so 

 many years past, the chapter in it on precious 

 stones comes from the pen of the well-known 

 authority on all that is concerned with gem-craft, 

 Dr. G. F. Kunz, of New York. With his cus- 

 tomary happy touch he interweaves the statistics 

 of imports with much that is of interest to the 

 economist and the mineralogist. 



^Ve have remarked before on a similar occasion 

 that the jewelry trade acts as a very sensitive 

 barometer indicative of the general state of trade 

 in a country. The unpreparedness of the Allied 

 nations for war, and especially of our own country^ j 

 had led to the placing of immense orders for muni- jyi 

 tions in the United States, and the consequent 

 keen demand for labour brought sudden affluence 

 to certain classes in the community. The result 

 was that the imports of precious stones in 1916 

 reached unprecedented heights. By the following 

 year the industrial position had become stabilised, 

 and the imports stood at a figure — just under 

 41 million dollars — which was about that of the 

 more prosperous years immediately preceding the 

 war. It must, however, not be forgotten that 

 prices had risen ver}' considerably. Thus Dr. 

 Kunz tells us that in Great Britain the cost of cut 

 diamonds had advanced between 30 and 40 per 

 cent., the increase being alx)ut equally divided 

 between the rise in wages and the advance in the 

 charge for the rough stones. 



Many have* remarked as a curious and unsatis- 

 factory state of affairs that in the days before the 

 war, whereas practically all the rough stones in the 

 world passed through London, very few indeed of 

 them were cut in England. A century ago things 

 were different ; then London vied with Amsterdam, 

 but for some reason or other — possibly the want 

 of a fostering hand — the industry pined and 

 withered, and a few years ago had all but passed 

 away. Under the stimulating care of Mr. 1 

 Bernhard Oppenheim, efforts are now being made 'M 

 to restore the industry, and a very promising 

 scheme, which has bad the practical support of the 

 powerful De Beers Company, is working at „ 



1 "The Production of Precious Stones for the Year iqi7." By Dr. G. F. ;■ 

 Kunz. " Mineral Industry," 1918, vol. xxvi., pp. 576-601. ' ■ 



