2IO PROTOPLASMIC ACTION AND NERVOUS ACTION 



conductivity, indicating a destructive or cytolytic effect. 

 In fertilized sea-urchin eggs, anaesthetics (chloral, 

 hydrate, alcohols, urethane) decrease the permeability 

 to water, as shown by the decreased rate of shrinkage 

 in hypertonic sea water containing the anaesthetizing 

 compound.' The penetration of acids into the pigment- 

 containing mantle cells of nudibranchs is also retarded 

 by anaesthetics.^ 



Changes of protoplasmic viscosity, as indicated by 

 changes in the readiness with which cell structures are 

 mechanically displaced (by centrifuging), have also been 

 observed, but the character of the change appears to 

 vary in different forms of protoplasm. In plant cells, 

 according to the observations of Heilbronn^ on seedHngs 

 and F. Weber^ on Spirogyra, ether in the anaesthetizing 

 concentrations increases the viscosity of the protoplasm; 

 in lower concentrations, on the other hand, it decreases 

 viscosity. This result agrees with the observations 

 of Ewart^ and others who find that weak solutions of 

 anaesthetics accelerate protoplasmic streaming while 

 stronger solutions retard or arrest it. In sea-urchin 

 eggs L. Heilbrunn^ has recently found that various 

 anaesthetics in concentrations sufficient to prevent cell- 



^R. S. Lillie, American Journal of Physiology, XLV (191 8), 406; 

 cf. p. 427. 



^ Crozier, Jour. Gen. Physiol., IV (1922), 723. 



sHeilbronn, Jahrb. wiss. Botanik, XLIV (1914), 357. 



4 F. Weber, Biochem. Zeitschrijt, CXXVI (192 1), 21; Ber. deutsch. 

 hofan. Ges.y XL (1922), 212. 



s Ewart, On the Physiology and Physics oj Protoplasmic Streaming in 

 Plants, Oxford (1903). Cf. also the observations by Demoor and others 

 cited in Czapek's Biochemie der Pflanzen, Jena (1913), p. 161. 



•^L Heilbrunn, Biological Bulletin, XXXIX (1920), 307. 



