532 



NATURE 



[December 26, 1918 



Dr. A. PlJPEB Ins described certain diffraction 

 phenomena observed with cultures of micro-organisms 

 In means of which the size of the organisms may be 

 ascertained without direct measurement (Med. Journal 

 of S. Africa, vol. xiv., 191S, p. 211). It was noticed 

 that certain colonies of a bacterial plate culture viewed 

 with ordinary daylight were colourless, but when the 

 plate was held in the beam of an electric arc at a 

 certain distance from, and at a certain angle to, the 

 source of light, the colonies exhibited a blue colour. 

 From theoretical considerations and control experi- 

 ments the conclusion was arrived at that the colora- 

 tion was due to a diffraction effect, the thin layer of 

 micro-organisms acting like a grating. For the better 

 observation of the effecl the following arrangement 

 was devised : The beam from an electric arc was 

 parallelised by means of a condensing lens and passed 

 through a hole in the proximal side of a closed box. 

 In the box the bacterial plate culture was suspended, 

 the glass of the dish being painted over with black 

 paint except at one spot placed opposite the beam. 

 Immediately opposite the transparent spot a second 

 lens ( nil. cted the rays, bringing them to a focus on 

 a transparent screen forming the distal side of the 

 box. On viewing the screen the spot in the axis of 

 the beam is colourless, but around this a series of 

 coloured rings spreads over the screen. Knowing the 

 focal length of the collecting lens, and measuring the 

 distance of any coloured ring from the axis, the size 

 of the slits can be calculated, and, for spherical micro- 

 organisms ; the size of the slits is found to be just 

 equal to the diameter of the organisms. This was 

 verified by observations on various micro-organisms, 

 the size found by the diffraction method and by micro- 

 metric measurement being practically identical. 



The last two reports of Bergens Museum, dealing 

 with the years 1916-18, bear witness to a restriction 

 of growth and activity caused by the war. In spite 

 of this, much valuable work has been accomplished, 

 and the educational influence of the museum has not 

 lessened. Among recent accessions are several repre- 

 sentatives of the anthropoid apes, notably a mounted 

 group of male and female gorilla with young, and a 

 fine skeleton of the male; a good mounted specimen 

 of the wart-hog (Phacochaerus) ; the Scandinavian 

 herbarium of the lately deceased J. R. Landmark, 

 who had continued to lite end his donations of plants 

 collected bv himself in remote districts ; numerous pre- 

 historic remains from recent excavations, particularly 

 a set of miniature greenstone axes, arrow-heads, 

 knives, scrapers, and flakes from Vaagso, Sond- 

 m0r. Dr. A. Brinkmann, head of the zoological 

 department, has started a collection of skeletons of the 

 various races of Norwegian domestic animals, 

 especially pedigree individuals, for which he hopes 

 to obtain the co-operation and pecuniary help of the 

 agricultural department. Such a collection, as was 

 recognised by Sir Ray Lankester when director of our 

 own Natural History Museum, is not merely of 

 popular interest and practical importance, but has a 

 value for the study of morphology and heredity. 

 During the period covered bv the reports the seismo- 

 graphic station connected with the museum has con- 

 tinued its work, and we think it well to conclude by 

 quoting a sentence that appears in each report : "The 

 Government has, on request, appropriated 4000 kroner 

 to the acquisition and installation of a new seismo- 

 graph, which will be purchased as soon as it is pos- 

 sible to obtain it from Germany." British instrument- 

 makers should note this remark. 



The little-known grain called quinoa (Chenopodium 

 quinoa) is the subject of an illustrated article in the 

 July issue of the Bulletin of the Pan-American Union 

 NO. 2565, VOL. I02] 



(vol. xlvii., No. i), a journal devoted to all aspects 

 of Latin America. It seems to be indigenous to the 

 highlands of South America, where it has been cul- 

 tivated since early times in Peru, Bolivia, Fcuador, 

 and Chile. It is very hardy, and thrives well at alti- 

 tudes of 11,000 ft., though in warmer climates it can- 

 not compete with maize. The natives who grow 

 quinoa use it in making a sort of bread, and it may 

 also be treated like oatmeal or rice. Quinoa is still cul- 

 tivated in a very primitive manner, and no attempts 

 have been made to improve the grain by seed selec- 

 tion. The United States Department of Agriculture, 

 however, is now experimenting with the grain in the 

 hope of finding suitable areas where conditions of soil 

 and climate will make it a profitable crop. 



Enormous quantities of timber have been used 

 during the great war. In the first few months all 

 available seasoned supplies were absorbed; for the 

 remainder of the period green, unseasoned timber had 

 to be employed, with the resultant inevitable high 

 percentage of wastage through cracking and shakes. 

 Large quantities of timber will be required for recon- 

 struction purposes and restarting industries. The 

 timber trade will therefore be in much the same posi- 

 tion for some time to come. It will not be possible 

 to await the period required for the natural seasoning 

 of the material. There are several methods in operation 

 for artificially drying timber by means of hot air. Mr. 

 Herbert Stone in the Quarterly Journal of Forestry 

 for October last discusses a method based on the use 

 of cold air. The method is worthy of consideration. 

 The plant required is a closed, double-roofed shed 

 dimly lighted from the north. At the end farthest 

 from the door a small refrigerating apparatus, such as 

 is used in cold storage, though of smaller dimensions, 

 is placed. By means of this a cold atmosphere is 

 created sufficient to cause the air moisture in the shed 

 to condense in hoar-frost, thus keeping the atmosphere 

 continually dry. The moisture coming from the pores 

 of the timber is thus constantly condensed in hoar- 

 frost and got rid of, the wood drying without the 

 risk of cracks and shakes, so often the accompani- 

 ment of hot-air drying. Mr. Stone is scarcely correct 

 in his assertion that in the future most of our timber 

 must be drawn from hot countries, where he recom- 

 mends the method for trial. For one thing, our chief 

 timber demands are for soft coniferous timber from 

 the temperate regions; and, for another, the method, 

 for various causes which will be readily appreciated 

 by those having acquaintance with forestry conditions 

 in the tropics, would be far more difficult of applica- 

 tion. 



The American Geographical Society has published 



an index to the first sixty-four years of the Bulletin 

 and Journal of the society. The periodical publica- 

 tions started in 1852, and for some years appeared 

 intermittently, but apparently no annual index was 

 published until 1895. The present volume will be wel- 

 comed by geographers as facilitating reference to a 

 most valuable set of periodicals. There are ret. p 

 to both subjects and authors. 



In a most interesting paper in the October issue of 

 the Geographical Review (vol. vi., No. 4) Mr. Edmund 

 Heller descusses the geographical barriers to the dis- 

 tribution of big-game animals in East Africa. Th< 

 paper is accompanied by a map showing the life-zones 

 I in the region. Mr Heller finds that climate is the 

 j chief controlling factor, and that it operates mainly 

 in limiting certain vegetable growths which afford food 

 ] and cover to animals. Large rivers, such as the Nile 

 ; and the Tana, are important barriers to big-game 

 ! mammals, but seem to have little influence on smalb r 



