W. A. Davis, A. J. Daish and G. C. Sawder 261 



alternative view tliat the sugars travel downwards as hexoses, althougli 

 meeting the diffusion difficulty, is not in accord with the absence of 

 invertase in the root. Strohmer's analyses, which showed that prac- 

 tically no reducing sugars occur in the root, and (iirard's conclusion 

 that saccharose is present in all parts of the plant in the earliest stages 

 of growth, also militate against this view. 



Gutzeit [1911], on theoretical grovmds based on the laws of diffusion 

 and osmotic pressure, contended that monosaccharides are formed in the 

 leaf and wander as such to the root where they are built up to cane 

 sugar. 



In the same year Rnhland flOU] contended that the sugar in the 

 sugar beet does not pass from the leaf in the form of saccharose but as 

 reducing sugars (perhaps largely as laevulose) ; the sugars entering the 

 root consist mainly of reducing sugars which are resynthesised to sac- 

 charose within the root. The cells of the leaves and stalks are stated 

 to be permeable to saccharose, raffinose, maltose and more or less to 

 all the hexoses tested, from which they are able to form starch. 

 Dextrose and laevulose are somewhat more diffusible than saccharose. 

 Light does not appear to exercise any influence on the permeabihty 

 of the cells, but on the other hand certain regulatory influences cordd be 

 detected. Ruhland states that the young growing root contains 

 invertase which gradually diminishes in quantity as the root matures 

 and is confined only to the growing parts. 



Deleano [1912], in a study of the respiration of the vine leaf (Vitis 

 vinifera), found that only a small increase of reducing power was caused 

 by inverting a solution obtained from the dried leaf material; this 

 pointed to the presence of very small quantities of cane sugar relatively 

 to the reducing sugars, which were present in large amounts, and as 

 he failed to isolate any cane sugar by Schulze's strontia method he 

 concluded that this sugar was in reality not present. We shall specially 

 deal with this point later. 



As distinct from the foregoing workers, who, on the one hand, regard 

 saccharose as the first sugar formed in the leaf, and, on the other, consider 

 the first product to be dextrose. Pellet [1913] considers that saccharose, 

 dextrose and laevulose are formed simultaneously in the leaf and that 

 the sugars descend in all three forms to the root, where the reducing 

 sugars are built up to saccharose. In a later paper Pellet [1914, 1] shows 

 that the view generally held, that the sugar cane contains no reducing 

 sugars, is based upon early work which was carried out prior to the 

 introduction of satisfactory methods of detecting or estimating reducing 



