292 The Carholniflrntrfi of fhc MaiKjohl Leaf 



2. As in the September picking tiie curve of iiexoses is always well 



above the curve of saccharose, the hexose being always largely in excess 



I.S. 

 of the cane sugar. Consequently, the ratio -^^ is always greater than 



c.s. 



unity; it fluctuates between the values 1-14 and 1-93; in September it 



ranged between 0-94 and 1-60, whilst in August the range was 0-13 



to 0-71. 



3. Series III differs from Series II mainly in the fact that during 



the earlier part of the day (9 to 11 a.m.) the saccharose increases faster 



I s 

 than the hexoses, as shown ])y tlic falling -'—^ ratio; subsequently the 



cs. 



total sugars remain nearly constant in amount until after sunset. The 



periodic fluctuation of the ratio ' " and the mutual interconversion of 



^ C.S. 



cane and invert sugar which it expresses are characteristic of the final 

 stage of growth only. Whereas, too, in the earlier pickings the propor- 

 tion of the total suf/ars falls off rapidly after the temperature niaxinuun 

 has been reached until the rise occurs in the neighbourhood of sunset. 

 in this case the total sugars remains nearly constant during tiie wliolc 

 afternoon, a balance being reached such that the sugars removed from 

 the leaf are equal in quantity to those being formed in it. This char- 

 acteristic of the last stages of growth is apparently due to the root 

 having relatively less capacity to remove the sugars from the leaf than 

 at earlier stages; in August and September the root was capable of 

 removing the sugars from the leaf in the afternoon faster than they 

 were formed; in October, tiio out-take and production just balance 

 one another. 



4. The total sugars present are at a far higher level in Series III 

 than in Series II; in Series II they formed Id to IC> ]icr cent., and in 

 Series III from!.') to 21 per cent, of the total vacuum-dried leaf matter. 



Variations during Complete Period of Growth. 



In Table IV we give the diurnal variations of the leaf carbohydrates 

 for the three stages of growth investigated. 



The principal conclusions which can be drawn as to the total varia- 

 tions during growth are as follows: 



1. The proportions of all the sugars present in the leaves increase 

 progressivelv from the first to the final stage of growth ; this is true of 

 saccharose, hexoses and pentoses. The extreme diurnal variation is, 

 however, greatest for the hexoses, pentoses, pentosan and matter 



