by Green Plants from certain Organic Compounds. 151 



intermediate product in the synthesis of carbohydrate by green plants 

 from C0 2 and H 2 0, but that it becomes immediately polymerised at 

 the moment of formation ; he does not, however, adduce any new 

 physiological experiments. 



Wehmer* has shown that assimilating plant cells do not form 

 starch from solutions of formic aldehyde or formose, and A. Meyer 

 that this is also true for solutions of aldehyde (acetic) and trioxy- 

 methylene. 



A. Meyer's paper (« Botan. Zeitung,' 1886, pp. 81, 105, 129, 145) 

 is frequently referred to throughout the following pages. 



It is well knownf that starch is formed by the leaves of green 

 plants when they are supplied with solutions of glucose or cane-sugar 

 (saccharon) : but very few experiments have been made to ascertain 

 how far this is true for other organic compounds. A. Meyer has 

 extended such investigations to the behaviour of leaves placed in 

 solutions of other carbohydrates and a few other compounds ; his 

 researches are frequently referred to throughout the following pages. 

 He found that starch is formed by leaves placed in solutions of 

 glucose, saccharon, mannite, inulin, and glycerin. 



Meyer's method consisted in placing leaves which had been de- 

 prived of starch in the dark in solutions of the substances. I have 

 extended the investigation to other substances — especially aldehydes 

 and substances related chemically to carbohydrates, using different 

 methods and devoting especial attention to the formation or not of 

 starch in the leaves of green plants when, organic substances are 

 supplied through the medium of their roots and not directly to the 

 leaves. 



E. Laurent^ has confirmed Meyer's observation that starch is 

 formed from glycerin. 



Wehmer's negative results with formic aldehyde and formose have 

 been already alluded to. 



Meyer (loc. cit.) has shown that starch is not formed by leaves 

 from solutions of rafiinose, inosite, erythrite, dulcite,§ trioxy- 

 methylene, aldehyde (acetic). 



Neither Meyer, Laurent, nor Wehmer describes any experiments 

 with reference to the supply of the substances used to the roots of 

 plants. 



In the following pages where the compounds used have also been 

 employed by Meyer, as described above, his results are stated in 

 giving details of experiments, but I did not generally make observa- 



* ' Berichte der Deutsch. Chem. Gesell.,' 1887, p. 2fil4. 



f Meyer's paper gives full references to previous experiments on this point. 



X ' Botan. Zeitung,' 1886, p. 751. 



§ Full information concerning the relation of these bodies to the glucoses is 

 given by Tollens (' Kandbuch der Kohlenhydrate '). 



