THE PHYSIOLOGY OF CELL-DIVISION 



V. SUBSTITUTION OF ANESTHETICS FOR HYPERTONIC SEA-WATER 



AND CYANIDE IN ARTIFICIAL PARTHENOGENESIS 



IN STARFISH EGGS 



RALPH S. LILLIE 



From the Marine Biological Laboratory, Woods Hole, and the Physiological Labora- 

 tory, Zoological Department, University of Pennsylvania 



I. INTRODUCTION 



The problem of fertilization presents various analogies with 

 the problem of stimulation — some superficial, others indicating 

 that the two processes possess certain fundamental physiolog- 

 ical features in common. In both cases the cell gives a qualita-* 

 tively constant or specific response to a change of condition 

 which itself need not be specific. Thus, a muscle contracts when 

 artificially excited by chemical, electrical, or mechanical stimuli 

 which never act upon it in the intact organism, in the same man- 

 ner as in response to the normal physiological stimulus or nerve- 

 impulse. Similarly, the egg-cell begins its characteristic cycle 

 of cell divisions after subjection to various artificial forms of 

 treatment, as well as after the normal contact and entrance of 

 the spermatozoon. It is a special peculiarity of the egg-cell 

 that these cell-divisions, once started, continue automatically in 

 a regular and predetermined rhythm and are associated with 

 the definitely directed and progressive processes of growth and 

 differentiation which constitute development. But this process, 

 however complex, is none the less the constant and distinctive 

 mode of response of the egg-cell, just as contraction is of the 

 muscle-cell. A relatively slight and non-specific disturbance 

 initiates in either type of cell its own characteristic and complex 

 type of physiological activity. 



23 



