640 



NATURE 



[February 12, 1920 



an interesting paper (Journ. Coll. Sci. Imp. Univ. 

 Tokyo, vol. xxxix., art. lo) has studied the chromo- 

 somes of maize and its relatives, and brings cyto- 

 logical evidence in support of Mr. Collins 's hypo- 

 thesis. Maize, as well as Euchlaena and Andropogon, 

 is found to have ten pairs of chromosomes, but those 

 of Euchlsena are longer than those of .-Xndropogon, 

 while in maize they are found to be of different 

 lengths, a pair frequently being composed of a longer 

 and a shorter chromosome. From this it is concluded 

 that maize is hybrid in origin, the two types of 

 chromosomes being traceable as in certain experi- 

 mentally produced animal hybrids. Some races and 

 individuals of sugar-maize are found to have eleven 

 or twelve pairs of chromosomes, which is attributed to 

 cross-segmentation of one or two pairs. It would 

 appear that in the origin of the many known varieties 

 of maize, a considerable number of which were grown 

 by the natives in different parts of the -American 

 continent, hybridisation and mutation may have gone 

 hand in hand. 



The United States Department of Ag:riculture is 

 publishing a folio atlas of American agriculture. 

 Part ix., section i., deals with rural population, and 

 contains thirty black-and-white maps and diagrams 

 based on the census returns of 1910. Among- the most 

 interesting- maps are two showing respectively the 

 increase and decrease in rural population between 1900 

 and 1910. Increase was mainly in the Pennsylvania 

 mining district, in the cotton belt, in the newlv 

 developing agricultural regions of the west, and 

 around cities. Decrease was most marked in the maize 

 and winter wheat region. It is explained by the con- 

 solidation of many small farms into a few large ones in 

 order to secure the full benefit of the use of machinerv 

 and large-scale production. The decrease in population 

 in these districts is mainly a measure of their produc- 

 tiveness. Of much interest, too, are the maps showing 

 the distribution of native white, foreign, and negro 

 stocks. For this purpose all people are classed as 

 foreign who either were born abroad or one or both of 

 whose parents were born abroad. A series of maps 

 shows the distribution of foreign population by 

 countries of origin. In both urban and rural popula- 

 tions the Germans are the principal nationality of 

 foreign stock, and the Irish the second. Except in the 

 case of Norwegians, Danes, and Swedes, the foreign 

 element is more noticeable in the urban than in the 

 rural population, k map illustrating the percentage of 

 the rural population unable to speak English shows a 

 high proportion in the west and north, particularly in 

 Wyoming, North Dakota, and Minneapolis, where the 

 Russian and Scandinavian elements are marked, and 

 in Pennsylvania, with its comparatively recent influx 

 of Slavs, Hungarians, Germans, and Italians. 



A GOOD geographic account of the Mackenzie River 

 basin has been drawn up by Messrs. C. Camsell and 

 Wyatt Malcolm for the Geological Survev of Canada 

 (Memoir 108, 1919). It has an eminently practical 

 bearing, and should guide those seeking new agricul- 

 tural lands or new fields for industry in the North- 

 West. 



NO. 2624, VOL. 104] 



M. L. DE Launay furnishes an important review of 

 the mineral resources of Alsace-Lorraine in the Revue 

 Scientifique (November 15, 1919, p. 673). It is in- 

 teresting to note that this article arose from a lecture 

 given in the recovered town of Metz, which lies at 

 the south end of the great field of oolitic iron-ore. 

 Sketch-maps are given of this field and of the 

 potassium and petroleum areas in the Rhine-vale. 



The importance of algae in the formation of lime- 

 stone is further emphasised by the publication of Mr. 

 W. H. Twenhofel's paper on " Pre-Cambrian and 

 Carboniferous Algal Deposits " (Amer. Journ. Sci., 

 vol. xlviii., p. 339, November, 1919). In the massive 

 cases here described it is held that the calcium car- 

 bonate does not enter into the tissues of the plant, 

 but is deposited, as in so many recent travertines, by 

 the lessening, through the activity of organisms, of 

 the capacity of the water to retain the salt in solu- 

 tion. The deposits are thus of the nature of laminated 

 encrustations. 



The Monthly Bulletin of the Hawaian Volcano 

 Observatory, which is always noteworthy for ii;s 

 unique illustrations, gives (in vol. vii., No. 8, .\ugust, 

 1919) a fine picture of a lava-rush in a cave, photo 

 graphed in June, 1919. The work of observation has 

 been rendered far more interesting for readers of 

 Nature since the publication of the views of the great 

 topographic model, in which the situation of the 

 scientific station is clearly shown (Nature of August 7, 

 1919, vol. ciii., p. 456). Mr. E. S. Shepherd gives a 

 number of analyses of the gases collected from 

 Kilauea in Bulletin No. 7, 1919, showing a "sur- 

 prisingly high " amount of water. 



The appearance of a memoir of 300 pages on "The 

 Geology of the Country around Lichfield" (Mem. 

 Geol. Survey, England and Wales, 1919, price gs.) 

 makes us once more wish that some relic of the Colby- 

 Portlock plan, hazarded in Ireland in 1840, had been 

 allowed to remain in our Geological Survey organisa- 

 tions. The scheme of the Irish Ordnance Survey was 

 undoubtedly too ambitious for the limitations of public 

 finance, and we now possess adequate unofficial 

 descriptions, from the Victorian county histories down 

 to the compact and clever Cambridge geographies, of 

 the greater part of England. The Lichfield country 

 is fully treated in this memoir from a geological point 

 of view, in continuation of the important modern 

 descriptions of the details of our British coalfields ; 

 but we should hail some expansion of Mr. G. Barrow's 

 twelve lines on the "distribution of the population." 

 The broad agricultural landscape, controlled bv 

 Triassic strata, that is so well seen from the tower 

 of Tamworth, is bounded on the east and west by 

 busy coalfields. The Roman highway leading to the 

 west undulates upwards to the bleak moor of Can- 

 nock, a "chase" long after the days when a king's 

 daughter held Tamworth Hill against the Danes. 

 English history is epitomised in the buildings on 

 this hill, now so well preserved as the municipal 

 museum ; and the changes in the density of population, 

 from the making of the Watling Street down to the 

 development of the coal-mines, are largely concerned 

 with geology, and deserve a chapter to themselves. 



