Volume VII FEBRUARY, 1916 Part III 



STUDIES OF THE FORMATION AND TRANSLOCA- 

 TION OF CARBOHYDRATES IN PLANTS. 



I. THE CARBOHYDRATES OP THE MANGOLD LEAF. 



By WILLIAM A. DAVIS, ARTHUR JOHN DAISH 

 AND GEORGE CONWORTH SAWYER. 



{RotJiamsted Ex-perimental Station.) 



Introduction. 



The object of the iuvestigations recorded in the present series of 

 papers was to throw Hght on fundamental problems — how carbo- 

 hydrates are formed in the foliage leaves of plants, how they are trans- 

 ferred to the reservoirs where they are stored (as saccharose in the sugar 

 beet or mangold^, as starch in the potato and the cereal crops and as 

 inulin in many Compositee such as the artichoke or dahha) and how 

 they are finally broken down and utihsed in subsequent growth. 

 A complete account of the work done in this field up to the year 1893 

 was given by Brown and Morris [1893] in their classical paper on "The 

 Chemistry and Physiology of Foliage Leaves." 



Sachs [1862] first proved that the production of starch in the chloro- 

 phyll granule depends on the action of light and that the starch formed 

 during the hours of sunhght is wholly or partially redissolved and 

 removed from the leaf during the night to supply the demands of the 

 growing points of the plant. Sachs regarded the starch as the "first 

 visible product of assimilation" and considered that all the carbo- 

 hydrate synthesised in the leaf passed through the starch stage; he 

 was of opinion that the starch disappeared in the form of sugar. 

 Schimper [1885] on the other hand held that starch is not only con- 

 verted into sugar in the plant but, from his observations of the increase 

 of starch in leaves supphed artificially with solutions of sugar, concluded 



* Both tlie sugar beet and the mangold are varieties of Beta vulgaris L. and appareniiy 

 have been derived by cultivation from the Beta maritinia. of our coasts. 



Journ. of Agrio. Sci. vii 18 



