1917] BROOKS—PERMEABIL ITY 239 
basis. The method of LreprscHKIn is therefore of extremely 
doubtful value. 
2. Recovery from Plasmolysis.—Recovery of plasmolyzed cells 
was first noted by Kies (17) in 1887, who found that glycerine 
was able to penetrate the plant cell. He was unable to detect 
recovery of.cells plasmolyzed by solutions of potassium nitrate or 
sodium chloride. Dr Vries (68) obtained similar results at about 
the same time. JANSE (16), whose work has been quite generally 
overlooked, demonstrated the penetration of potassium nitrate, 
sodium chloride, and saccharose by observations on the recovery of 
plasmolyzed cells of the marine algae Chaetomorpha aerea and 
Dictyota sp., and Spirogyra nitida, Tradescantia discolor, and 
Curcuma sp. It was thus conclusively shown that at least some 
inorganic salts can penetrate living cells of many types of plants. 
OVERTON (48) was unable to observe any cases of recovery of 
cells plasmolyzed by inorganic salts. He supposed this to be due 
_ to the insolubility of such salts in lipoid substances, which he 
supposed to constitute the plasma membrane. It has been pointed 
out by OstEeRHOuT (41) that OvERTON in all probability over- — 
looked the recovery of the cells which he used, confusing the sub- 
sequent “false plasmolysis,” due to the injury of the cells, for a 
continuation of the true plasmolysis. OstERHOUT showed thata _ 
great variety of salts penetrate and cause recovery. OsTERHOUT _ 
also showed that the rate of recovery of Spirogyra cells was more 
rapid when a salt of one of certain monovalent kations was used 
to produce plasmolysis than when a calcium salt was similarly 
used.* It was impossible to establish more than the most general 
quantitative relations in these experiments. Recently Frrrmnc (8) 
has conducted an extensive series of investigations on the per- 
meability of cells of Tradescantia discolor L’Heritier (Rhoeo discolor 
_ Hance). His data may be most easily understood if stated graph- : 
ao ically. lates 8 strips of — were ae aks = 
