'Sl-i The (Jarl)uhij(lrat(^ iij tlic MaiKjold Lraf 



5. The proportion of saccharose in the leaf tissue follows the 

 temperature curve closely during the daytime ; the proportion of hexoses 

 increases faster than the temperature, in such a way that the curve 

 showing the ratio of hexoses to saccharose is itself practically parallel to 

 the temperature curve. 



6. The facts brought forward can apparently' be best explained by 

 Brown and Morris' view that saccharose is the primary sugar formed in 

 the mesophyll of the leaf under the influence of the chlorophyll ; it is 

 transformed into hexoses for the purpose of translocation. This 

 transformation occurs in the veins, mid-ribs and stalks, the proportion 

 of hexoses increasing more and more as the root is approached. The 

 sugar enters the root as hexose and is therein reconverted into sac- 

 charose ; once in this form the saccharose is not able to leave the root 

 until it is put under contribution for the second season's growth. 



7. These views arc in accord with de Vries' micro-chemical obser- 

 vations as to the nature of the sugars in the different tissues but entirely 

 in contradiction with those of Strakosch, which are considered to rest 

 on no secure foundation. 



8. They also agree wifli Parkin's results with the snowdroj), with 

 Pellet's analyses of the sugar cane, with f'olin's results with the sugar 

 beet and our own observations with other plants such as the vine ( Vitis 

 vinifera), potato, dahlia, etc., which store their carbohydrates in other 

 forms (dextrose, starch and inulin). 



9. As regards the mechanism by which saccharose is syuthesised 

 from the hexoses, it is improbable that this change is effected by invertase 

 by a process of reversible zymo-hydrolysis. The entire absence of 

 invertase from the root is against this view. 



III. Pentoses form only a small proportion of the total sugars in 

 the tissues; they are probably formed from the hexoses and appear 

 to be precursors of the pentosans. 



