300 RALPH S. LILLIE. 



positive ions immediately external to the egg-surface. De- 

 polarization would then permit interaction to take place. ^ Such 

 a conception, while in a sense diagrammatic, helps at least to 

 explain how a non-specific agency, provided it only alters 

 sufficiently the boundary-layer of the egg, can be the means 

 of initiating such a highly specific process as development. 



The discussion of this question can hardly be considered 

 complete without some reference to the case of hypertonic sea- 

 water. As Loeb has shown, exposure to this agent forms a 

 supplementary treatment which is remarkably favorable with 

 some eggs, especially sea-urchin eggs. This treatment seems to 

 occupy a special position among the parthenogenetic agents. 

 It may either precede or follow the membrane-forming treat- 

 ment,^ and in some way it puts the egg into a condition which is 

 favorable to subsequent development; this action seems quite 

 independent of the nature of the membrane-forming or activating 

 agent, and so far it has received no satisfactory explanation. 

 Loeb has shown that a purely physical abstraction of water is 

 not the only factor concerned; a chemical factor, apparently 

 involving oxidation, is essential; free oxygen must be present 

 during the treatment, and the eflfective times of exposure vary 

 at different temperatures according to the chemical temperature- 

 coefficient.^ Some hypothesis as to its mode of action seems 

 required; and I suggest the following, which is consistent with 

 the foregoing point of view, and has not, to my knowledge, yet 

 been put forward. 



1 The inorganic analogy would be, e. g., the interaction between solution and 

 metal at the surface of the plate in a battery when the circuit is closed. While the 

 battery is at rest (with open circuit), interaction between (e.g.) sulphate ions and 

 zinc is prevented by the polarization at the surface of the zinc plate. The tendency 

 to this ionic interaction i s compensated by the polarization, the zinc ions being 

 held back by the negatively charged plate. Similarly, mutatis mutandis, with the 

 reactions at the cell-surface, or other surfaces (adsorption-surfaces) within the cell. 

 The facts of stimulation afford in general strong evidence that the chemical proc- 

 esses in the living cell are largely dependent on changes in the electrical polar- 

 ization of the limiting membranes. Cf. my paper in the Journal of Biological 

 Chemistry, 1913, Vol. 15, p. 237. Also, for a more general discussion of this ques- 

 tion, the article entitled "The Physico-chemical Conditions of Stimulation," in 

 the Popular Science Monthly, 1914, p. 579. 



^ Cf. Loeb, "Artificial Parthenogenesis and Fertilization," Chapter 11; Archiv 

 fiir Entwicklungsmechanik, 1914, Vol. 38, p. 409. 



'"Artificial Parthenogenesis and Fertilization," Chapter 11. 



