W. A. Davis, A. J. Daish and CI. C. Sawyer 313 



the cane sugar increased with the temperature proportionately faster 

 than the rate of formation of cane sugar itself. 



We are also aware that it is possible to explain the predominance of 

 saccharose in the early stages of growth (Series I), regarding the hexoses 

 as primary products, by assuming that as the root is insufficiently 

 developed to deal with them, they are transformed into the storage 

 form, saccharose, in the leaf itself, so as to relieve the osmotic pressure. 

 The formation of starch in the very early stages of growth, contrasted 

 with its entire absence later on, is a similar phenomenon, having as its 

 object the diminution of the excess sugar formation. But although this 

 hypothesis is a possible one, it appears that the whole body of facts we 

 have recorded, especially the data regarding translocation, find a better 

 explanation in the view that the cane sugar is a primary product and 

 gives rise to the hexoses by inversion than by assuming the hexoses to 

 be primary products in the mesophyll and the saccharose to be formed 

 from them. 



Summary. 



1. The formation and translocation of the sugars in the mangold 

 have been studied under actual conditions of growth, in which trans- 

 location was normal. 



2. Starch is entirely absent from the leaf after the very earliest 

 stages of growth. As soon as the root begins to develop so that the 

 sugars formed in the leaf can be translocated to it, starch disappears 

 almost entirely from the leaf. Maltose is entirely absent from leaf, 

 mid-ribs and stalks at all stages of growth and at all times of night and 

 day. 



3. During the early stages of growth of the mangold, when leaf 

 formation is the principal function, saccharose is present in the leaf 

 tissue in excess of the hexoses. Later in the season, when sugar is 

 being stored in the root, the reverse is true, hexoses largely predominating 

 in the leaf. 



4. In the mid-ribs and stalks the hexoses always predominate 

 greatly over the saccharose and vary widely in amount during the day 

 and night, and throughout the season, whilst the saccharose remains 

 practically constant. In passing from leaves to mid-ribs, from mid- 

 ribs to the tops of stalks and from the tops of stalks to the bottoms, 

 the ratio of hexoses to saccharose steadily and rapidly increases. As 

 the season advances the predominance of the hexoses in leaf, mid-ribs 

 and stalks becomes more and more marked. 



