CERTAIN MEANS BY WHICH STARFISH EGGS NATU- 

 RALLY RESISTANT TO FERTILIZATION MAY BE 

 RENDERED NORMAL ANT) THE PHYSIOLOG- 

 ICAL CONDITIONS OF THIS ACTION. 



RALPH S. LILLIE. 



(From the Marine Biological Laboratory, Woods Hole, and the Physiological 

 Laboratory, Department of Zoology, University of Pennsylvania.) 



Last summer at Woods Hole, while investigating the influence 

 of ether and other anaesthetics in protecting the unfertilized eggs 

 of starfish against the cytolytic action of pure isotonic sodium 

 chloride solution, 1 I observed that toward the end of the breed- 

 ing season the eggs often proved .abnormally resistant to this 

 solution, withstanding in some instances exposure of more than 

 three hours to 0.5577* NaCl without losing the power of develop- 

 ment on fertilization; in normal eggs this solution typically 

 causes complete cytolysis and coagulation of the protoplasm in 

 two hours or less. Other characteristic abnormalities of be- 

 havior were found to be associated w r ith this abnormal resistance 

 to salt solutions. Usually a large proportion of such eggs failed 

 to undergo maturation in sea-water, and of those which matured 

 only a small proportion developed to a free swimming stage on 

 fertilization, and the resulting larvae were largely abnormal. Also 

 the mature eggs, if left unfertilized in sea-water, frequently failed 

 to die and break down within the usual time, but remained clear 

 and apparently normal in appearance for an unusually prolonged 

 period. It is well known that unfertilized mature starfish eggs 

 undergo spontaneously a characteristic cytolytic alteration, ac- 

 companied by a darkening or coagulation of the protoplasm, 

 which is typically complete within twelve to fifteen hours after 

 deposition; 2 in contrast to this behavior a considerable propor- 

 tion of the eggs under consideration often remained clear and 

 uncoagulated in sea-water for twenty-four and in some cases for 

 forty-eight hours. These several peculiarities, (i) failure of 



1 American Journal of Physiology, 1912, Vol. 30, p. i. 



2 Cf. J. Loeb, Archiv fur die gesammte Physiologic, 1902, Vol. 93, p. 59. 



