104 Journal of Agriculture, Victoria. [10 Feb., 1917. 



1838 to 1870 the increase in the average percentage of sugar in the roots 

 was small, namely, 8.8 to 10.1 per cent. During the second period (1868 

 to 1888) Vilmorin's discovery that, although the sugar content of the 

 beet was an hereditary character, it is necessaiy to repeat the selection 

 of seed-bearing plants at frequent intervals in order to maintain the 

 improvement. 



To ascertain the richness in sugar of the mother plants, Vilmorin 

 floated the roots in baths of salt or in sugar solutions of known specific 

 gravity. This method was replaced by a process of analysis of small 

 sections of the roots by means of the Polarimeter. 



These methods were used by Vilmorin with great success between 

 1870 and 1888, and during this period the average content of the sugar 

 beet rose from 10.1 to 13.7 per cent. The final stage of improvement 

 of the sugar beet was begun when the breeder took into account the 

 ancestral heredity of the mother plants. Tlie method consisted in valu- 

 ing the different reproducing plants separately, keeping the seeds pro- 

 duced by each apart, and determining by direct experiment the faculty 

 of transmission which each plant enjoyed. 



Occasionally the breeder meets with roots the characteristics of which 

 are abnormally desirable. Such plants are subjected to careful genea- 

 logical selection in order to ascertain whether their descendants show 

 these desirable qualities on an even greater scale. If so, these roots are 

 made heads of families and the starting points of new and improved 

 races. By these methods of individual selection, controlled by chemical 

 analysis, the average sugar content of the beets has been raised from 

 15.2 per cent, to 18.5 per cent. As individual roots contain up to 26 

 per cent of sugar, there is every reason to believe that the limits to im- 

 provement have not yet been reached. The application of the above 

 methods of selection has improved the sugar content of beets to such 

 an extent that it is now possible for sugar grown by white labour from 

 sugar beet to compete on equal terms with sugar grown from cane by 

 black labour in the tropics. 



Phylloxera. 



Now consider the interesting illustration of the part played by science 

 in the viticultural industry. In 1863 there were rumours of a mysterious 

 disease on the vines in the Bordeaux district of France. It proved to 

 be the terrible scourge of the vine — phylloxera. It rapidly spread 

 through France, and in twenty years (1884) no less than 2,500,000 acres 

 of vines were absolutely destroyed. The total damage due to the ravages 

 of this pest amounted to £400,000,000 — twice the amount of the war in- 

 demnity paid by France in the Franco-Prussian war. From France it 

 spread through Europe, Africa, and, finally, to California and Australia. 



It broke out in Geelong in 1877, in Rutherglen in 1898, and it has 

 destroyed about 30,000 acres in Geelong, Bendigo, and Rutherglen. 



That will give some idea of the disastrous effect of phylloxera. It 

 may be explained that phylloxera is an American insect found east of the 

 Rocky Mountains, and is classed among the aphides. It lives on the 

 leaves of the American vines, and causes curious galls on the leaves. 



A feature of the life-history of the pest is the remarkable power it 

 has of multiplying asexually, i.e., by Parthogenesis. In its life cycle 

 many generations of parthogenetically produced progeny are formed, and 

 this accounts for the enormous rate at which it sweeps through a country. 



