58 Physiologie. 



2) All concentrations, the Solutions being changed once, exactly 

 half way through the experiment. 



3) All concentrations, the Solutions being never changed. 



The whole experiment was repeated three times at intervals of 

 three weeks. so as to gain Information as to seasonal effects. The 

 amount of growth varied considerably under the differing conditions, 

 and the experiments upheld the earlier contention of Hall and 

 Under wood that the concentration of the nutrient Solution influen- 

 ces very greatly the rate of growth of plants, and also that the 

 amount of growth is strictly limited by the quantity of available 

 food when the nutrient Solutions are dilute, even when the balance 

 of the Solutions approximates to a constant level. Starvation effects, 

 due to insufificient nutriment, are evident in much stronger concen- 

 tration than has been admitted by some observers. The action of 

 diiferent high concentrations of constant balance has not yet been 

 determined, and it is uncerlain whether there is an optimum strength, 

 above and below which growth falls off, or whether there is a ränge 

 of concentrations between which the plants will make equally good 

 growth. W. E. Brenchley. 



Bosinelli, G., Die Wirkung des freien Schwefels auf das 

 Pflanzen Wachstum. (Intern, agrar-techn. Rundschau. VI. 7. p. 

 1025-1026. 1915.) 



Verf. studierte die Frage, ob die Anwendung des Schwefels 

 durch eine bessere Ausnützung des Bodens für die landwirtschaft- 

 liche Praxis zu empfehlen sei. Die Versuche im Freien und in 

 Vegetationsgefässen (Avenaj Mais, Sinapis arvensis, Vicia sativa, 

 etc.) ergaben keinen Zusammenhang zwischen der verabreichten 

 Schwefelmenge und der Ernteerhöhung. Letztere wurde allerdings 

 konstatiert. Auf die Eiweissbildung und Chlorophyllbildung hatte 

 der Schwefel keinen Einfluss. Der Schwefel erleichtert wohl die 

 Ueberführung des organischen Stickstoffs in Ammoniakstickstoff, 

 aber diese Umsetzung hört bald auf. Daher ist der praktische 

 Nutzen des Schwefels in wirtschaftlicher Hinsicht ein recht 

 zweifelhafter. Matouschek (Wien). 



Davis, W. A., Studies of the formationand translocation 

 ofcarbohydrates in plants. 2. The dextrose-laevulose 

 ratio in the mangold. (Journ. Agric. VII. 3. p. 327 — 351. 1916.) 



Inconsistences in the proportion of laevulose to dextrose in 

 plant material are attributed to the presence of optically active 

 substances other than the sugars, which are not precipitated by 

 the substances, such as basic lead acetate, which are used to purif3'' 

 the Solutions analysed. Such bodies as acid amides or amino acids 

 form soluble lead salts and so would not be precipitated. These 

 impurities occur to some extent in the leaves, but they are much 

 more abundant in the midribs and stalks. 



Analyses of samples taken at different times of the day show 

 Variation in the ratio dextrose/laevulose. In some cases a dextro- 

 rotatory impurity is probably present, but at certain times of the 

 day a laevo-rotatory impurity seems to predominate. In the midribs 

 and stalks it is probable that the proportion of the dextro-rotatory 

 impurit}^ is greater than in the leaf, because the dextrose always 

 appears to be vert much in excess of the laevulose, The fluctuations 

 in the ratio of dextrose to laevulose are more probably caused by 



