PHYSIOLOGY OF CELL-DIVISION 399 



est the surface; suppression of the radiations by etherization 

 involves suppression of divisional activity; incomplete division 

 is correlated -with incomplete development of asters; in eggs 

 containing several asters of varying sizes the depth of the furrow 

 adjacent to each aster is proportional to the development of 

 the latter; in eggs whose asters have been artificially suppressed 

 by ether the rays may subsequently redevelop, and the effect 

 on the form of the adjoining cell-surface is then in direct ratio 

 to the development of the rays.®'' All of these facts indicate 

 clearly the existence of an influence emanating from the aster, 

 proportional to the development of the latter and its distance 

 from the surface. 



The hypothesis that substances diffusing from the astral 

 centers reach the surface and there cause local lowering of sur- 

 face-tension is naturally suggested by such facts as the foregoing. 

 The evident correlation of this influence with the development 

 of the radiations indicates, however, that the electrical factor, 

 rather than the mere diffusion of surface-active substancfes, 

 is the essential one. Moreover, the influence is apparently 

 in the direction of increasing rather than decreasing surface- 

 tension, since local increase of curvature in a fluid droplet im- 

 plies increased tension,®' i.e., traction toward that area. The 

 hypothesis which seems to me most consistent with all of the 

 facts considered is briefly as follows: the effect of the astral 

 area in locally increasing surface-tension is due to the local 

 electrical field, negative centrally, of which it is the expression; 

 such a field, on approaching sufficiently near the cell-surface — ■ 

 of which the polarization is positive externally, negative inter- 

 nally — will compensate this polarization to a greater or less 

 degree and hence increase the surface-tension. The periphery 

 of the astral field is positive (due to the slight surplus of more 

 rapid or more readily penetrating cations); we may therefore 

 regard the astral areas as a source of cations (possibly hydro- 

 gen ions from CO2, etc.), which increase the positivity of the 

 protoplasmic layer immediately beneath the cell-surfa,ce, i.e., 



*" Instances of all of these phenomena are described in Wilson's second paper, 

 loc. cit.; cf. especially pages 367, 368, 372, 381. 



" Cf. footnote 14; also Freundlich's Kapillarchemie, p. 212. 



