(514 RALPH S. LILLIE 



change in the condition of the hpoids — possibly in the inter- 

 relations between lipoids and proteins — is the primary effect 

 produced and that this change then initiates some specific chemi- 

 cal reaction which determines directly or indirectly the char- 

 acteristic surface-changes of fertilization, namely, secretion of 

 cortical material, formation of fertilization-membrane, tempor- 

 ary change in osmotic properties of the plasma-membrane with 

 accompanying electrical depolarization. 



This view emphasizes the analogy between the activation of 

 the resting egg and the general process of stimula'tion.^^ In 

 stimulation the primary event is a depolarization of the limiting 

 membrane; similarly in the fertilization-process the electrical 

 variation accompanying the above surface changes forms most 

 probably the critical or 'releasing' event on which the rest of 

 the process automatically follows. One gains the impression 

 that in the resting egg-cell, as well as in the. resting muscle or 

 nerve, certain substances are hindered from interacting by the 

 electrical polarization at the cell-surface; just as in a battery 

 with open circuit the chemical reactions on which its opera- 

 tion depends are held in check by the polarization at the sur- 

 face of the plates :22 that is, the passage of ions into or out of 

 solution is thus prevented and with it all effects, chemical and 

 other, dependent on the flow of electricity through the circuit. 

 Under analogous conditions in the living cell a brief depolariza- 

 tion might suffice to release the impediment to the chemical 

 interaction forming the primary event in the response — whether 

 to stimulation or (in the case of the egg-cell) to fertilization. It 

 is noteworthy that in many if not in most irritable cells the 

 response is specific and constant and independent of the char- 

 acter and intensity of the stimulus; that is, recent research 

 indicates that the ''all or none" law applies to irritable elements 

 in general, 23 and not only to heart-muscle, and it may be said 



-' For a fuller discussion of this analogy, cf. my recent paper in the Journal of 

 Exp. ZooL, 1913, vol. 15, p. 23. 



-^ The solution-tension of the ions being compensated by the electrostatic at- 

 traction between the plate and the oppositely charged adjoining layer of solution. 



2' Cf. especially the recent articles from the Cambridge Physiological Labora- 

 tory by Lucas and Adrian in the Journal of Physiology. 



