THE PHYSIOLOGY OF CELL DIVISION 45 



also showed a distinctly greater protective or anti-cytolytic action 

 than ethyl alcohol. ^"^ 



It is remarkable that hypertonic sea-water, in the numerous 

 experiments performed last summer, never proved more than 

 moderately effective with starfish eggs, and in no case effected 

 so great an improvement as occurred in favorable experiments 

 with cyanide or anesthetics. With sea-urchin eggs, on the other 

 hand, hypertonic sea-water of the above concentration gives 

 highly constant and favorable results. It would seem that the 

 action of hypertonic sea-water in artificial parthenogenesis is 

 in no sense exceptional or distinctive, but that it is for mainly 

 incidental reasons that this treatment proves so highly favorable 

 with certain species of eggs, while with others a quite different 

 form of treatment is more effective. Why such different agen- 

 cies should produce the same physiological effects cannot at pres- 

 ent be said in any detail. The common factor in the production 

 of these effects is probably the presence of a membrane whose 

 physiologically important properties, such as electrical polariza- 

 tion, are influenced by agencies of widely different kind in essen- 

 tially the same manner. The case of stimulation again affords 

 perhaps the best analogy; here polarization-changes at membranes 

 are demonstrably concerned, and we find that a large variety of 

 stimuli may cause the same effect. The possibilities of variation 

 in polarization, qua polarization, are limited; a given agency may 

 either decrease the polarization of a membrane or increase it, 

 and the degree, rate, and periodicity of these changes may vary. 

 What is significant is that the number of variables is constant 

 and limited. It is thus not surprising that a variety of external 

 changes should produce the same physiological effect, if this 

 effect depends on a change of polarization. The phenomena under 

 consideration in the present paper appear to illustrate this 

 principle. 



Cf. American Journal of Physiology, 1913, pp. 264 seq. 



