5i8 



Nature 



[June 24, 1920 



thus to spread the pear-tree beyond its present limits 

 and to obtain from a more robust stock an increased 

 thickness of edible flesh, and perhaps improvement in 

 flavour; and parcels of P. indica seed were sent to 

 the southern Lnited States to test this means of fruit 

 development. But the wild Persea is fast disappear- 

 ing from our forests through sheer improvidence, and 

 its priceless pink-tinted mahogany will soon be extinct. 



Ihe alligator pear — the "midshipman's butter" of 

 other days — is mainly eaten in Madeira as a breakfast- 

 table fruit, generally with pepper and salt, and is 

 especially to be commended as a sapid adjunct to a 

 well-made salad, garnished with segments of the 

 fruit as with hard-boiled egg, and sprinkled with the 

 edible flowers of Cercis siliquastruni when available. 



The Portuguese authorities will some day realise 

 that the fertile valleys into which these mountain- 

 slopes are cloven may be more profitably occupied 

 than with sugar-cane by the custard apple, alligator 

 pear, and other plants the perishable product of Avhich 

 Madeira only, from its situation, can supply in per- 

 fection to the European markets ; and our perennial 

 green peas. Cape gooseberries, February strawberries, 

 hognuts, and broad beans will then be available in 

 profusion while the Northern markets still wear their 

 wintry aspect. Michael Grabham. 



Madeira, June 7. 



Eye-Colour in Bees. 



Every biologist is now familiar with the colour- 

 variation in the eyes of Drosophila, and the remark- 

 able contributions to biological theory which this 

 variation has made possible. It is not so well known 

 that among the Anthophorid bees there are striking 

 differences in eye-colour, which must have arisen in 

 a manner analogous to those of Drosophila. These 

 differences usually characterise species ; thus in the 

 genus Centris one form has the eyes crimson, another 

 green, another grey. In Anthophora two closely 

 related species from New Mexico differ, one having 

 the eyes green, while in the other they are dark 

 purplish. There are other differences, and the species 

 are quite distinct. I have just obtained evidence of 

 mutation in eye-colour within the species. Antho- 

 phora porterae, Ckll., is a large species with clear 

 green (olive-green or pea-green) eyes. The varieties 

 Watsoni and semiflava agree with the typical form 

 of the species in this respect. However, on May 23 

 of this vear, at White Rocks, near Boulder, Colorado, 

 Miss Marie Chandler found a male with the eyes 

 dark bluish-green (sea-green). This mav be called 

 mut. Thalassina. On drying, after death, the eyes 

 became grev marbled with black. 



T. D. A. COCKERELL. 



University of Colorado, Boulder. 



British and Foreign Scientific Apparatus. 



It may be said at once with emphasis that British 

 scientific instruments cannot be made in factories at 

 the present wage-rates and under prevailing labour 

 conditions at twice the pre-war prices if identical in 

 quality and construction. Mr. Ogilvy discloses the 

 same "fact with regard to German instruments when 

 he states in Nature of June 3 that the wages rates of 

 Germany are 400 per cent, hierher than in 1914, and 

 that working conditions are difficult in every way. 



The only reason that German firms can sell in 

 English money at from 60 per cent, to 100 per cent, 

 above pre-war rates is on account of the benefit they 

 have under to-dav's rate of exchange, which values the 

 mark at i^d. only. It is obvious that German firms 

 are doing remarkably well for themselves _ by selling 

 in^England at about" twice the pre-war price. ^ 



The question is not one of free trade, prohibition, 

 NO. 2643, VOL. T05] 



or import under licence, but whether the scientific 

 instrument manufacturing of this country is to con- 

 tinue or not. It is recognised that scientific apparatus 

 is a necessity to the nation, and should properly be 

 maintained as a "key industry." The manufacturers 

 have the courage and the enterprise, and have been 

 making preparations for production by new methods 

 on a large scale for many months under exceedingly 

 difficult conditions, but with the assurance that some 

 degree of protection would be given to them. 



1 have before me as I write an offer of 11,935 prism 

 binoculars lying in London by leading German 

 makers, all at the same price and far below the cost 

 at which similar binoculars can be made in this 

 country at the present time. This, surely, is a case 

 of "dumping," 



It must never be forgotten that the scientific instru- 

 ment makers in this country were among the foremost 

 in the production of precise instruments for the war. 

 Works were enlarged and plant increased to make 

 instruments of which the Government had never 

 encouraged the manufacture in this country, pre- 

 ferring to buy from Germany in times of peace ; and 

 the more effectually a comparatively small firm did 

 its work in war-time, the more it is handicapped 

 now. Several firms are laden with premises and plant, 

 and have excess profits liabilities which are difficult to 

 meet in cash, while capitalists will not put monev 

 into scientific instrument .manufacturing businesses 

 under present conditions. 



Production would be hastened on a scale com- 

 mensurate with the needs not only of this country, 

 but also of the world, if these facts were faced and 

 met; and it is the opinion of scientific instrument 

 makers that some degree of protection should be 

 afforded during the period that the mark and the 

 franc have such a depreciated value. 



There are no "trusts" in the British optical world, 

 as a correspondent in Nature suggests ; there is 

 severe competition between all manufacturers. 



British manufacturers have never been slow in 

 throwing open their works for the inspection of those 

 who are interested, and if your correspondents and 

 readers could be induced to pay a visit to some of the 

 works in this country and see exactly what is going 

 on and the possibilities that exist, they might be led 

 to take a view of the subject which would offer 

 encouragement to the hardly pressed, but still 

 optimistic, British scientific instrument maker. 



If any readers of Nature should wish to visit 

 optical works, and would send a note to the secretary 

 of the British Optical Instrument Manufacturers' 

 Association, Ltd., 2-3 Duke Street, St. James's, 

 arrangements would quickly be made. 



F. W. Watson Bakfr. 

 (W. Watson and Sons, Ltd.) 



313 High Holborn, London. W.C. 



Applied Science and Industrial Research. 



Prof. Soddy and Major A. G. Church both say in 

 Nature of June 3 that my letter published on May 27 

 confuses the issue. It may be so: I have never 

 known a controversy in which each side did not, 

 sincerely, accuse the other of the sins of irrelevancy 

 and confusion. I have no desire to enter on a detailed 

 discussion of personal views. My sole aim was to 

 raise certain Drincinles that seemed to me in danger 

 of being overlooked. I think Prof. Soddv's sugges- 

 tion will meet the case : that readers of Nature who 

 are interested should obtain a copy of the full report 

 of his address. Thev can then judge for themselves 

 how much or how little occasion there was to justify 

 my letter. J. W. Williamson. 



3 Canterbury Mansions, N.W.e^ June 12. 



