386 SCIENCE PROGRESS 



hours before death of the cell takes place, there is only a quite 

 gradual rise in permeability. 



An examination of the permeability to single salts of the 

 cells of roots of Lupinus albus, and the palisade cells of the 

 leaves of Acer platanoides and Salix babylonica was made by 

 Troendle (" Sur la permeabilite du protoplasme vivant pour 

 quelques sels," Arch. Set. Phys. etNat., Ser. 4, 45, 38-54, 1 17-32, 

 191 8). The ordinary plasmolytic method was used. It was 

 found that potassium chloride and sodium chloride were 

 absorbed for the first ten minutes at a uniform rate, but that 

 after that time the permeability decreased, the relation between 

 time and penetration of salt being approximately a logarithmic 

 one. From this result Troendle concluded that a phenomenon 

 of irritability is concerned, as the results agree with Weber's 

 rule. The author suggests that the salts irritate the proto- 

 plasm, which react to this irritation by the transportation of 

 salt to the interior of the cell. It must be admitted that these 

 conclusions are based on insufficient evidence. Troendle also 

 compared the rate of entrance of a number of different salts. 

 From his results he came to the conclusion that the rate at 

 which any salt entered the cell depends both on the kation and 

 the anion, the rate of intake of salt depending partly on the 

 position of the kation in the periodic classification. 



In a later paper (" Der Einfluss des Lichtes auf die Per- 

 meabilitat der Plasmahaut und die Methode der Permea- 

 bilitats-Koeffizienten," Vierteljahrsch. d. Naturforsch., Ges. in 

 Zurich, 63, 187-213, 191 8) the same author corrects his earlier 

 results in which he had assumed that the osmotic concentra- 

 sion of sucrose was exactly proportionate to the molecular con- 

 centration, but he finds that his results are not appreciably 

 altered and consequently that his former conclusions are 

 still valid. 



Miss M. Williams ('* The Influence of Immersion in Certain 

 Electrolytic Solutions upon Permeability of Plant Cells," Ann. 

 of Bot., 32, 591-9, 191 8) investigated permeability of cells of the 

 petioles of the leaf of London Pride. Sections of the organ in 

 question, when immersed in a 2 per cent, solution of ferric 

 chloride, do not show any reaction between the ferric chloride 

 and the tannin contained in some of the cells until the lapse of 

 two or three days at least. But after the sections are treated 

 with solutions of certain salts, the reaction is given much more 

 rapidly, owing to an increase in the permeability of the cell. For 

 purposes of comparison an arbitrary degree of increased per- 

 meability was chosen, namely, that at which an immersion for 

 three minutes in the ferric chloride solution brought about a 

 reaction with the tannin of the cell, so that a blue coloration 

 was produced. The time taken to bring about this increase in 



