I 



Influence of Certain Carbohydrates on Green Plants 11 



presented concludes that phase of the subject concerned with the absorption 

 of certain carbohydrates and their influence on plant growth. As 

 compared with previous investigations on this subject, a wider range 

 and a larger number of plants have been employed; the study has been 

 extended to the influence of weaker concentrations on growth; the con- 

 tinued influence of sugars on respiration has been studied ; and an attempt 

 has been made to obtain some data on the comparative ease of assimilability 

 of different sugars. The last-named phase of the work is being more 

 intensively studied in the light of the present investigation. Incidental 

 observations have been made also on the influence of sugars on color pro- 

 duction in the plants studied and on the excretion of enzymes, and the 

 noteworthy fact developed that galactose is toxic to the plants and th^t 

 its poisonous action can be antidoted. The prime object, however, has 

 been to confirm the earlier work on the direct absorption of sugars, and 

 to extend these studies to other plants. 



HISTORICAL 



De Saussure (1804) found that Bidens cannabina and Polygonum persi- 

 caria apparently absorbed sugar from an aqueous solution of the same. 

 His work was of course not conducted under sterile conditions, and doubt- 

 less much of the sugar reported as being absorbed disappeared through 

 fermentation. This work attracted no particular attention because of 

 its agreement with the humus theory. 



The possibility of absorption of organic substances by cuttings, leaves, 

 and floral parts of plants was fully established by Boehm (1883), Meyer 

 (1886), E. Laurent (1887), and Schimper and others (Pfeffer, 1900). 

 The investigations of these men were designed to tkrow light on the question 

 of the first product of photosynthesis. They found that starch was 

 produced when the plant was offered any one of a number of organic 

 substances, notably the sugars and glycerin. 



After Boehm (1883) reported the absorption of sugar by means of the 

 roots, Acton (1889) demonstrated the production of starch in deamy- 

 lated plants at the expense of organic substances absorbed by the roots. 

 He employed rooted plants of Quercus rdbur, Cheiranthus cheiri, Euphor- 

 bia helioscopia, Phaseolus vulgaris, and Acer pseudoplatanus. He noted 

 that glucose, saccharose, and glycerin were absorbed and starch was 

 produced in the leaves of the plants when they were maintained in liquid 



