280 The Carboliydratoi of the Mamjold Leaf 



course pursued bv the curves in question. Tiic total variation of the 

 cane sugar during the day is only from 2-5 to 3-1 per cent., but the 

 methods of working adopted are sufficiently delicate to show a regular 

 and progressive variation between these extremes. 

 The outstanding features of the sugar curves are: 



1 . The rise of sugar which first occurs, followed by a rapid falling 

 oft' along approximately straight lines. Practically the whole of the 

 reducing sugar disappears during the night, but the saccharose only 

 falls to about one-half of its maximum value {3-1 per cent, falls to 

 1-5 per cent.). 



2. The quantity of saccharose is always greater than that of hexose 

 sugar (seven times as great at 4 a.m., \-b times as great at 10 a.m.), 

 so that the saccharose curve is always well above the hexose curve. 

 But the hcxoses increase at first more rapidly than the saccharose and 

 later on fall oft' more quickly. The curve showing tlie ratio of hexoses 



to saccharose (— -- ratio] is itself more or less closely parallel to the 



temperature curve, a fact which becomes even more strikingly marked 

 in Series II. Thus the proportion between the sugars — the increase of 

 the hexoses relatively to the saccharose — seems itself to be a function 

 of the temperature, or perhaps of the photo-chemical activity of which 

 the temperature is in this case a rough measure. We shall discuss this 

 point later (see p. 312). 



3. The total fluctuations of the sugars are very small, especially 

 in comparison with those foimd later in the season. 



The saccharose increases from 2-.5 per cent, to 3-11 per cent, and 

 falls at night to 1-50 per cent. 



The hexoses increase from 0-77 per cent, to 2'16 per cent, and then 

 fall at night to 0-20 per cent. 



The fluctuation of the hexoses is far greater than of the saccharose. 



Pentosan Curve and Curve of Mailer Insoluble in Alcohol. 



PVom Fig. 4 it is seen that in .s])ite of tlie considerable increase in 

 the sugars which occurs during the day from fi a.m. to 2 ]).ni., there is 

 simultaneously a marked increase in the percentage of matter insoluble 

 in alcohol ; this increase runs closely parallel with an increase in the 

 pentosans. The curve of insoluble matter in fact closely resembles the 

 pentosan curve, a resemblance which becomes far more strongly marked 

 in the September picking (see Fig. 5, p. 283), when the curves are 



