NATURE 



[March 2, 19 16 



shadow of an observer, and found it to be 23°. They 

 also pegged out the curve and proved it a hyperbola, 

 and showed that half the angle of the cone was ap- 

 proximately 42°. The gossamer was spread quite 

 evenly over the field, and at the brightest part of the 

 morning — which was still and cloudless — a slight 

 secondary bow could be distinguished. 



Mr. N. T. Porter has sent me some photographs of 

 gossamer taken on the lawn of Downing College, 

 Cambridge, one morning some weeks before ; when 

 a similar ground rainbow was seen. He adds that 

 he has noticed the gossamer fall in thick clouds on 

 several occasions when out shooting in the early morn- 

 ing. A. E. Heath. 



Physical Laboratory, Bedales School, Petersfield. 



THE APPLICATION OF SCIENTIFIC 

 METHODS TO THE IMPROVEMENT 

 OF THE SUGAR BEET. 



AN important memoir on the production of 

 improved seeds of the sugar beet is pub- 

 lished by M. E. Schribaux in the Bulletin de la 

 Societe d' Encouragement.^ The memoir gives 

 one of the best accounts that has vet appeared 

 of the methods of selection which have proved 

 so successful in improving the quality of the 

 sugar beet during the past fifty years. It is to 

 these improvements that the remarkable growth 

 of the beet sugar industry is largely due. They 

 provide an admirable illustration of what can be 

 effected by applying rigorous scientific methods 

 to agricultural practice and industry on the large 

 scale, and demonstrate scientific control pushed 

 to a limit which only a few years back would 

 have been regarded as impracticable or even 

 impossible. This can be best appreciated when 

 it is stated that in selecting the best beet roots 

 to be used as seed-producers, every single root 

 which appears suitable on morphological or 

 other grounds is subjected to chemical analysis. 

 Often more than 3000 roots are analysed each 

 day ; for this purpose a staff of three men, 

 assisted by ten women or children, is necessary, 

 and the price of each analysis works out at about 

 four centimes. 



The accompanying diagram (Fig. i) shows at 

 a glance the improvement that has been effected 

 in the quality of the beet since it was first grown 

 as a raw material of the sugar industry. During 

 the interval from 1838 to 1870 seed growers con- 

 fined their attention almost entirely to physical 

 characteristics, such as form ; these efTorts were 

 not without success, and led to the adoption of 

 the type which, after its selection by Rabethge 

 and Giesecke, became known as the Klein Wanz- 

 lehen, from the district in Saxony in which it 

 was grown. During this period, too, it was 

 noticed that the largest roots are always the poor- 

 est, and a medium-sized root only was therefore 

 aimed at. From 1838 to 1870, the increase in the 

 percentage of sugar was but small, namely, from 

 8'8 to lo'i per cent. 



The second period of selection opened with the 

 discovery by Louis de Vilmorin of the fact that, 



' "Ta TTodurt'on des graines de betterave in'^usirieHes assur^e par 

 I'aericulture franca'se." Hy E. Schribaux. (/>«//. Soc. d'Encoujagemeni. 

 vol. cxxiv., No. 4, pp. 178-251) 



NO. 2418, VOL. 97] 



although the saccharine quality of the beet is a 

 hereditary character, in order to maintain the 

 improvement of the stock it is necessary to repeat 

 the selection of the seed-bearing plants {porte- 

 graines) at frequent intervals. He created the 

 celebrated race Vilmorin amelioree associated 

 with his name, by adopting a strictly scientific 

 control in place of the empirical one which had 

 previously determined selection. To ascertain the 

 richness in sugar of the mother plants Vilmorin 

 at first floated the roots in baths of salt or sugar 

 solutions of known specific gravity. This method 

 was soon replaced by a process of ascertaining 

 the density of the juice expressed from small 

 sectors of the roots, and this, in turn, gave way 

 to the polarimetric process which is now uni- 

 versally in use. The methods introduced by Vil- 

 morin were adopted with great success between 



1858 1848 1858 1868 1878 1888 1898 1908 1912 



h-. 



PHYSICAL IPHYSICAL, CHEMICAL 



AND ^ AND 



I CHEMICAL I PHYSIOLOGICAL SELECTION 

 I SELECTIOH I 



Fig. I.— Variation of richntss in sugar oHndustrial sugar beets. 



1870 and 1890, especially in Germany; during 

 this period of twenty years the sugar content 

 was raised from lo'i to 13*7 per cent. 



Up to this date, however, attention was given 

 only to direct heredity, selection being confined 

 to the mother roots. The next great step in the 

 improvement of the beet was introduced by 

 taking into account the ancestral heredity of the 

 seed-bearers, pedigree or genealogical selection 

 l:>eing adopted. This method was defined by 

 Vilmorin as follows : " It consists in valuing the 

 different reproducing plants separately and in- 

 dividually, keeping the seeds produced by each 

 apart, and determining by direct experiment the 

 faculty of transmission which each plant enjoys." 

 From 1898 to 1912, by this individual method of 

 selection, aided and controlled by chemical ana- 



