W. A. Davis, A. J. Daish and Q. C. Sawver 275 



of the roots began. lu ordinary cases, the error of sampUng in the case 

 of the saccharose estimations is probably neghgible, and in the case of 

 the reducing sugars not greater than 2 or 3 per cent, of the actual values. 



Results of Mangold Experiments. 



The mangolds used were Sutton's Yellow Globe and were grown on 

 Plot 9 of Barn Field^, which is manured with minerals and nitrate of 

 soda. The pickings were taken so as to obtain information as to the 

 sugars in the leaves and stalks at different stages of growth. During 

 the early period of growth the plant is mainly occupied in forming 

 leaf, and the root is relatively small, consisting merely of a tap root 

 and root hairs ; later on the leaf formation reaches a maximum and the 

 root then develops rapidly and stores sugar abundantly, httle increase 

 taking place in the leaves. Records of the ratio of leaf to root during 

 growth in recent seasons are not available for the mangold, but the 

 systematic experiments on the closely alhed sugar beet carried out in 

 France and Germany in 1913 and recorded by Vivien [1913] show that 

 from June 17th to August 26th, whilst the leaves steadily increased in 

 weight, the ratio of the weight of leaves to root fell from 6-06 to 1-61 ; 

 during the next month, August 26th to September 30th, when growth 

 was finally complete, the weight of the leaves was actually falhng, but 

 the root increased by large amounts. The ratio of leaves to root fell 

 in this period from 1-61 to 1-04. When the roots are hfted the weight 

 of the leaves is nearly the same as the weight of the roots. In the case 

 of the mangold, which stores a much smaller proportion of sugar, the 

 weight of leaves at hfting is always much smaller than the weight of 

 the root — generally only about one-third to one-quarter, as shown by 

 the data given in the note below and the records of the Rothamsted 

 experiments. Tbe relationship of the leaf to root in the sugar beet and 

 mangold is in accord with the fact that in the beet the percentage 

 of sugar is roughly three to four times that of the mangold (yellow 

 globe), so that the ratio of leaf to root and the percentage of sugar are 

 roughly proportional values. 



Our samples were taken at three different dates, so as to give data 

 representing three distinct stages of growth : 



Series I. Early growth, when leaf formation predominates. Samples 

 were taken every two hours during a complete period of 24 hours, 



' This plot receives as manure 500 Ib.s. of potassium sulpliate, 200 lbs. of magnesium 

 sulpliate, 200 lbs. of sodium chloride and 550 lbs. of sodium nitrate to the acre. The 

 yield was on this plot in 1912: roots 17-95 tons, leaves 6-08 tons per acre; in 1913, roots 

 21-2, leaves 7-00 tons per acre. 



