i2 4 SCIENCE PROGRESS 



recently. Stiles and Jorgensen (Ann. Bot. 29) find that the 

 cells of potato tuber absorb hydrogen ions very rapidly, and 

 according to a simple exponential relation between time and 

 the concentration of the acid. The rate of absorption is in- 

 creased about 2*2 times for a rise of io° C. between o° and 

 30 C. Apparently, since the rate of the reaction depends 

 merely on the temperature coefficient and the concentration 

 of the acid, the quantity of the substance (presumably the 

 plasma membrane) with which the acid reacts remains constant, 

 suggesting that either this substance is present in such large 

 quantity as compared with the acid that the amount changed 

 is relatively small, or that the substance formed as a result 

 of the absorption is broken down again almost as soon as 

 formed. Osterhout (Bot. Gaz. 61), continuing his work on per- 

 meability in Laminaria, finds that suitable concentrations of 

 anaesthetics produce a marked decrease of permeability, which 

 may amount to 15 per cent, or even more, this condition 

 lasting for a long time if the concentration is not too high, 

 and being easily and quickly reversed by replacing the tissue 

 in sea-water, while high concentrations produce irreversible in- 

 crease of permeability. Osterhout suggests that anaesthesia in 

 general may be due to decrease of permeability, this hindering 

 the production and transmission of stimuli, which in turn 

 depends upon movement of ions in the tissues ; also that the 

 irreversible increase with high concentration is due to the 

 anaesthetic combining chemically with the protoplasm, the effect 

 on permeability changing after a certain amount has combined. 

 Spoehr (Plant World, 19) discusses and criticises the well- 

 known formaldehyde theory of photosynthesis, and throws grave 

 doubt on the possibility of a condensation of formaldehyde to 

 sugar in plants. In his experiments, sugar appeared when lead 

 hydroxide, calcium hydroxide, and potassium carbonate were 

 used as " catalysts," but it appeared both in darkness and in 

 light, and the main reaction in all cases was the oxidation of 

 the formaldehyde to formic acid. Brown (Amer. Journ. Bot. 3) 

 has published the results of an elaborate research on the move- 

 ments of the well-known Venus' fly-trap (Dioncea), the chief 

 being that stimulation is at once followed by decrease in osmotic 

 pressure of the cells of the concave region of the leaf, and later 

 by growth-enlargement of these cells, and the appearance in 

 them of a large quantity of starch, also that the mechanism 



