W. A. Davis, A. J. Daish and (I C. Sawyer 309 



in the root, but in the organs containing invertase — the leaves and 

 stallcs — and translocated as such. Our results prove that the sugars 

 approaching the neighbourhood of the root become richer and richer 

 in hexoses, and, as we shall shortly show, it is in the form of hexoses 

 that the sugars actually enter the root. With regard to the theory 

 that the cane sugar is formed by reversible enzyme action, the experi- 

 ments quoted by Robertson, Irvine and Dobson to show a synthetic 

 action of the enzyme-sludge prepared from parts of the sugar-beet are 

 by no means conclusive ; even if such synthetic action occurred (and its 

 amount seemed to be exceedingly small) it is not shown that the synthetic 

 action was due to invertase or that it was reversible. In all ordinary 

 concentrations such as would be met with in the plant cells, invertase 

 acts practically completely in the one direction only — that of hydrolysis. 

 It woidd seem indeed that the root of the sugar beet or mangold possesses 

 some special mechanism for synthesising cane sugar — some special 

 enzyme such as the " saccharogenic enzyme" of Barbet [1896]. But 

 there is as yet little direct evidence available in favour of such a theory. 

 That the reducing sugars conveyed by the stalks actually enter the 

 root is shown by the recent analyses of Colin [1914], who states that 

 when the root is exceedingly small (souches filiformes) the reducing 

 sugars form one-fifth of the total sugars in the root. The proportion of 

 reducing sugar natiirally falls as the season advances, because the 

 accumulation of the cane sugar stored diminishes the relative proportion 

 of reducing sugar. But there is little doubt from the analyses we give 

 in Table V that the reducing sugars, which more and more predominate 

 in the stalks as the root is approached, actually enter the root as such 

 throughout the season. Pellet [1914, 2], at the congress of sugar chemists 

 in 1914, criticised the work of earlier workers, such as Girard, and 

 pointed out that their failure to detect reducing sugars in the root was 

 owing to their having used insufficiently delicate methods of analysis; 

 he stated that reducing sugars are always present in the root in amounts 

 varying from 0-05 to 0-30 per cent., depending on the meteorological 

 conditions. When the hexoses are being rapidly formed and enter the 

 root at a rate which is in excess of the ability of the "saccharifying 

 power" of the root to cope with, the reducing sugars accumulate for 

 a short time, and high values such as 0-3 per cent, are obtained. On 

 other days, when the rate of production of the hexoses is less, the 

 "saccharifying power" of the root is able immediately to transform 

 the whole of the hexoses into saccharose, and lower values such as 

 0-02 to 0-03 per cent, are found. 



