302 The Carbolnidnttes of the MatHjold Leaf 



mid-ribs in the foriii of the less rapidly diffusible sugar saccharose, and 



is there inverted to reducing sugars ; these pass downwards towards 



the root at a greater velocity than the cane sugar can enter to take 



their place. 



4. The clearest light on the nature of the first sugar formed in the 



leaf and the changes which occur in translocation is obtained by com- 



I s 

 paring the values obtained for the ratio -^^ in the leaves, mid-ribs and 



c*s. 



top and bottom halves of the stalks at the same hour of the day. Such 



a comparison shows at once that Ihe proporlion of hexoses to cane sugar 



is always very small in the leaf as compared with its value in the mid-rib, 



that it is less in the mid-rib than in the stalk and less in the top half of the 



stalk (nearest the leaf) than in the bottom half nearer the root. Thus to 



take one instance only, on August "iGth at (5 a.m. the value of the ratio 



i.s. 



-^ is only 0-.307 in the leaf, whereas it 

 C.s. 



is 1-42 in the tops of 



stalks and 2-48 in the bottoms. It is unfortunate that in Series I no 

 mid-ribs were examined, but on comparing Table VI with Table VII 

 and the values for stalks and mid-ribs in Table VIII, it is seen that the 



proportion of hexoses to saccharose ( ^— ' j is always far higher in the stalks 



than in the mid-ribs at the same time of day. The stalks in these cases 

 (Series II and III) were the whole stalks, so that the results give merely 

 the average values throughout their length. As seen from Table V, 

 the proportion of hexose in the stalks rapidly increases in passing down 

 the stalks towards the root. A comparison of Table VI with Table V 

 also shows how greatly the ratio of hexoses to saccharose increases in 

 the stalks as the season advances and the storage of sugar in the root 

 becomes more and more the predominating function of the plant; 

 thus for example: 



