PHYSIOLOGY OF CELL-DIVISION 395 



about themselves, just as if each were an independent center of 

 chemical activity influenced by some single change to which the 

 entire cell responds. According to the present hypothesis, this 

 inciting change is the surface-depolarization resulting from tem- 

 porary increase of permeabiUty. Many experimental facts 

 are in harmony wdth this view. Wilson's observations on the 

 abnormal eggs of Toxopneustes seem especially significant; 

 he describes certain eggs which fail to divide, but in which 

 nevertheless the nucleus and centrosomes pass through alter- 

 nating periods of activity and rest similar to those of normal 

 eggs;^^ the appearance of amoeboid changes of form, indicating 

 alterations of surface-tension, at the times when radiations 

 develop, and their disappearance at the interkinetic periods 

 when the nuclei reform and radiations disappear, indicate 

 clearly an interdependence between surface-changes and the 

 development of radiations. The influence of anaesthetics on 

 these phenomena points in the same direction. Evidence 

 from many sides indicates that the essential basis of anaesthesia 

 in cells and irritable elements consists in an alteration of the 

 plasma-membrane, rendering the latter resistant to changes 

 of permeability and electrical polarization; hence stimulation 

 and other effects dependent on changing polarization are pre- 

 vented.^^ The fact that in both normal and abnormal eggs the 

 development of radiations is prevented and existing radiations 

 are suppressed by etherization,^" is thus in harmony with the 

 view that these phenomena — like the phenomena of stimula- 

 tion — are a consequence of altered surface-polarization. We 

 may infer that the plasma-membrane of the etherized egg is 

 no longer capable of variations of permeability and polariza- 

 tion; and that for this reason the chemical changes in the cen- 

 trosomes, normally initiated in this way, are no longer possible. 

 The facts of cytology must be considered in the light of results 

 in other fields of cell-physiology — especially those relating to 



*^ Archiv fiir Entwicklungsmechanik., 1901, vol. 12, p. 546. 



*^ Cf. my review in Science, N.S., 1913, vol. 37, p. 959; also Amer. Journ. 

 Physiol., 1913, vol. 31, p. 275, and Biological Bulletin, 1916, vol. 30, p. 311. 



^^ Cf. Wilson, Phenomena of fertilization and cell-division in etherized eggs, 

 Archiv f. Entwicklungsmechanik., 1901, vol. 13, p. 353. 



