312 The CarhohijfJrati'H of (he MangohJ Leaf 



which show that in passing from the leaf tissue to mid-ribs and stalks, 

 the proportion of hexoses to saccharose progressively and rapidly 

 increases. If Strakosch's views were correct we should expect to find 

 the hexoses in excess in the leaf tissue and the cane sugar steadily 

 increasing on the way to the root. Actually the reverse is true. In 

 the earhest stages of growth, saccharose predominates in the leaf and 

 even in the later stages of growth when the hexoses are in excess in the 

 leaf, the proportion of cane sugar to reducing sugars is at its muximum 

 in the leaf tissue and falls steadily in passing from the leaf to mid-rihs, 

 and from mid-rihs to stalks. If Strakosch's ideas were correct it is 

 surprising to find, as the season advances and the importance of the 

 storage function increases, the proportion of the reducing sugars to 

 cane sugar in the stalks actually increasing; thus: 



Stalks, Aug. 20th-27tli 

 (average top and 

 bottom halves) Stalks, Sept. lOth-lltli 



Ratio— ... ranges from 1-8 to 2-7 4-25-5-27 



Hexoses ... 5-35-13-1 "„ 20'5-26-7 % 



The following comparisons of the ratio of hexoses to saccharose 

 for leaf, mid-ribs and stalks are incomprehensible on the basis of 

 Strakosch's views. 



Leaf Mid-ribs Stalks 



August 26th-27th ... 0-26-0-69 — 1-8 -2-7 



September lOth-lItli 1-11-1-60 2-55-3-72 4-25-.5-27 



October llth-12tli ... M4-1-93 2-75-3-24 3-99-t-S6 



We are aware that against the view that cane sugar is a primary 

 product may be urged the fact that in Series I and II of our results the 

 hexoses appear to increase after sunrise faster than the saccharose, so 

 that they seem to be more responsive to the stimulus of light than the 

 saccharose. But this is probably due to the fact that each molecule of 

 saccharose gives rise on inversion to two molecules of hexose; when 

 the separate proportions of dextrose and laevulose are considered (see 

 following eominunication) they appear to follow the proportion of cane 

 sugar more closely. The actual values found for cane sugar represent 

 merely the excess of cane sugar formed over that inverted to hexoses; 

 as we have already pointed out the j)roj)()rtion of hexoses to saccharose 



——] during the daytime (that is the period of photosynthetical action) 



follows very closely the temperature curve, as if the rate of inversion of 



