by chemical methods. 103 



If the lack of concord between the duplicates is not due to 

 the samples having been taken from too small a number of roots, 

 it must be due to some defect in the method of taking the 

 samples. The most obvious variation likely to occur would be an 

 error in the angle at which the boring was taken, and inspection 

 of fig. 1 which shows the distribution of sugar in a mangel as 

 determined from the examination of a number of roots, makes it 

 clear that such an error would easily account for great variation, 

 since a slight alteration in the inclination of the line A B, along 

 which the boring was taken, would make a very great difference 

 in the composition of the core. 



The authors have therefore taken their cores horizontally 

 through the greatest diameter of the root, i.e. along the line CD. 

 This position is much more definite and easy to fix, and the varia- 

 tion in composition in this region is much less marked. 



Since adopting this precaution it has been possible to obtain 

 much more concordant results. 



In sampling the varieties duplicate lots of 50 cores were 

 taken from each variety, very large and very small roots being 

 avoided. 



Each bundle of 50 cores was cut across transversely. One 

 half was dried at 65° C to determine the percentage of dry matter. 

 The other half was pulped, and the juice expressed for the deter- 

 mination of the percentage of sugar. In the mangel the sugar was 

 determined by the polarimeter, after clarification with basic lead 

 acetate, and the result checked by polarising again after inversion 

 by Clerget's method. It was found in every case that the sugar 

 present consisted almost entirely of cane sugar, a small amount, 

 usually under o per cent., of a dextro-rotatory sugar, shown to be 

 dextrose by its cupric reducing power, being also present. 



In the swedes the sugars were found to be cane sugar, dextrose, 

 and levulose in such proportions that the juice possessed practically 

 no rotatory power. The polarimeter therefore could not be used 

 for their determination, and recourse was had to the rapid volu- 

 metric method described in the preceding paper. 



The authors regret that they were unable to determine the 

 yield per acre except in the case of the mangels grown at the 

 University Farm. 



Mangels. The following tables give the yields per acre of 

 mangels at the University Farm, and the percentages of dry 

 matter and sugar in the mangels grown there and at the three 

 stations in Norfolk. 



