Physiologie. 535 



'& 



cotnme l'a fait Blackman. La fonction d'interversion du Saccharose 

 donne les meraes courbes. A une certaine temperature, il y a un 

 maximum bien net, raeme dans le cas oü toute destruction est ab- 

 seilte. Henri Micheels. 



Paine Sydney, G., The permeability of the Yeast cell. 

 (Proc. roy. Soc. B. LXXXIV. p. 289-307. 1911.) 



Experiments on plasmolysis of yeast indicated that the cell wa s 

 impermeable by inorganic salts generally, while it allowed of the 

 ready diffusion of such substances as alcohol, acetone, and urea. A 

 quantitative method was developed which enabled the author to 

 determine the distribution of the solute between the yeast cells and 

 the surrounding liquid when yeast had been immersed for some 

 time in a Solution of the solute. 



The ratio of the concentration of the liquid within the cells to 

 that of the liquid outside was in the case of alcohol 0.85, of urea 

 0.89 (Proc. Roy. Soc. B. 84. 1911. 455), while for such salts as 

 sodium Chloride, ammonium sulphate, sodium phosphate and arse- 

 nate in decimolar concentration, the ratio was less than 0.1 and in 

 0.3 molar concentration approximately 0.2. The amount of salts thus 

 shown as entering the cells is believed to be either adsorbed on the 

 surface or contained between the outer cell envelope and the more 

 or less contracted plasma'tic layer. 



Experiments with hexosephosphate were particularly interesting 

 since this substance is present in yeast and is readily hydrolised 

 and fermented by yeast-juice. The fact that when this substance is 

 added to yeast there is no evidence of its being fermented would 

 seem to indicate that it had not been able to penetrate through to 

 the seat of fermentative activity. It thus seems highly probable that 

 the apparent entrance of this substance, which was well demonstra- 

 ted, is merely a surface phenomenon. Author's abstract. 



Rees, R., Longevity ofseeds and structure of seed coat. 

 (Proc. roy. Soc. Victoria. XXIII. p. 393—414. 1911.) 



A large number of seeds were experimented with. The author 

 confirms the Statement 1) that macrobiotic seeds belong for the 

 most part to Leguminosae, 2) that the highest percentage of germi- 

 nation occurs amongst cuticularised seeds, and 3) that the more 

 impermeable the cuticle the higher the percentage of germination. 

 The impermeability of hard seeds was due in all cases examined 

 to the presence of cutin, and the degree of impermeability depends 

 not only on the thickness of the cuticle, but probabty on the Pro- 

 portion of waxy substance present. A. D. Cotton. 



Samsonow, A„ Ueber den Becquerel-Effekt in Uranylsul- 

 fat-, Chininsulfat- und Chlorophyllösungen. (Heidelberg, 

 1911. 36 pp.) 



Taucht man in rohe Chlorophyllösung (auch in Lösung der 

 Aethylchlorophylliden) zwei Elektroden und belichtet die eine, so 

 ändert sich die Potentialdifferenz beider. Dieser „Becquerel-Effekt" 

 (tritt bei Carotinoidenlösungen nicht auf) lässt sich als Elektronen- 

 abspaltung von den Chlorophyllinen und auswählende Absorption 

 der einen oder der anderen Ladungsgattungen seitens der Elektro- 

 den deuten. Im Anschluss an Tswett's nachstehend referierte Hy- 



