934 REPORT— 1900. 



2. On the Ej^ect of the Closure of Stomata on Assimilation. 

 By Dr. F. F. Blackman and Miss MATTHiEi. 



3. Formation of Starch from Gly collie Aldehyde by Green Plants. 

 By Heney Jackson, B.A., B.Sc. 



Glycollic aldehyde or diose has recently been isolated in a crystalline state,^ 

 and more recently it has been shown by the author - that this substance, under the 

 influence of dilute alkalis, very quickly condenses to two synthetic hexoaes, one of 

 which, and acrose, is identical with fructose 



It therefore became a matter of interest to find whether green plants could build 

 up starch if allowed to remain for a time in a solution of this simple sugar. The 

 following are the results of a few experiments. Leaves of tropceolum and clover, 

 which had been depleted of their starch by growing in the dark, were floated in a 

 3 per cent, aqueous solution of diose, control experiments being made with cane 

 sugar, glycerine, and distilled water ; the whole series being kept in the dark for 

 six days. They were then tested by Sachs's method, and it was found that those 

 floating in pure water were quite starchless, those in glycerine almost so, but those 

 growing in diose had accumulated starch in the tissues, though not to the same 

 extent as those placed in cane sugar. 



Spirogyra was placed in a 1 per cent, solution of diose in an atmosphere free 

 from COo, and after five days in the light had accumulated starch, whilst the 

 control experiment in distilled water showed only a small quantity of starch. In 

 the last set of experiments spirogyra was grown in an atmosphere free from 00,^, 

 but kept in the dark. After a week the control specimen, which bad been in dis- 

 tilled water, was starchless, whilst that growing in the sugar had formed large 

 quantities of starch. 



4. On the Effect of Salts on the CO^ Assimilation of Ulva latissima, L. 

 By E. A. Newell Arber, B.A. 



The primary object of these experiments was to obtain a general idea of the 

 extent to which the power of CO., assimilation is dependent on the absorption of 

 nutrient salts. 



It was found that an inhibition of the CO., assimilation could be caused by the 

 presence or absence of certain salts in the medium. 



Ulva was rendered free from starch, and exposed to light in media containing 

 known proportions of salts. The amount of CO^ assimilation which took place 

 was gauged by the starch accumulation. In distilled water only a very small 

 amount of starch was formed, while in tap-water containing traces of nutrient 

 salts _ the inhibition was only slight. Distilled water was not found to have any 

 injurious effect on the plant. The presence of NaCl in the medium was found to 

 be essential in order to obtain the maximum of CO^ assimilation. From indirect 

 evidence a total or almost total absence of NaCl caused a very marked inhibition 

 in all cases ; and no other salt could be found to replace NaCl in regard to CO3 

 assimilation. 



The absence of any one of the following salts, MgCl.j, MgSO^, CaS04,or KCl,from 

 sea water did not inhibit the assimilation. The presence of a nitrate in appreciable 

 quantity in the medium caused an inhibition. Ammonium nitrate was found to 

 be fatal. KNO3 caused a more marked inhibition than NaNOa; the inhibition 

 being least marked in the case of Mg(NOJ„. 



' Fenton and Jackson, J. Chem. 80c. Trans,, 1899. 

 * J. Chem. 80c. Trans., 1900. 



