Variability of Eggs and Sperm of Sea-Urchins. 85 



J. Loeb and H. Wasteneys (5) believed that the different results on 

 the effects of weak and strong bases on the oxidation of eggs of the 

 sea-urchin may be due to differences in the eggs. 



Wasteneys (8) later, in working upon the oxidation of sea-urchin eggs, 

 concluded that the variations in his results were due to differences in 

 sensitiveness of eggs of different females and perhaps to differences of 

 temperature. 



R. S. Lillie (3), from a study of the rate of swelling of eggs in diluted 

 sea-water, also concluded that the variability hi rate was due to the 

 condition of the eggs. 



In studying the fertilizin phenomenon, F. R. Lillie (1) arrived at a 

 more adequate appreciation of the nature of this variability when he 

 held that the condition of the eggs, whether ripe or immature, fresh or 

 stale, with or without jelly, is more important than concentration of 

 the eggs. Elsewhere (p. 568) he remarked that "the condition of the 

 gonads is the most variable thing in summer sea-urchins." 



R. S. Lillie (3) made a notable contribution when he concluded that 

 resistance to osmotic disruption hi dilute sea-water was "a convenient 

 index of the physiologic condition of the plasma membrane" and that 

 "an intimate connection exists between the general physiologic con- 

 dition of the egg and the physiologic state of the plasma membrane." 



We are not justified in assuming that all ripe eggs freshly removed 

 from the bodies of the sea-urchins are in a uniform or nearly uniform 

 physiologic condition or that at a subsequent interval in sea-water 

 the eggs continue to remain in a fairly uniform physiologic condition. 



This study and later ones have forced upon me the conclusion that 

 these assumptions are without basis. Eggs freshly removed from the 

 body are not in the same physiologic condition, as measured by any of the 

 tests I have proposed. Given an originally limited variability of the 

 eggs for the chemico-physical explanation of which see Loeb and 

 Chamberlain (4) which variability I shall term the primary varia- 

 bility, further variations and types of variants are superimposed by 

 reason of the fact that the eggs do not all ripen 1 at the same tune 

 within the body. Further variability is due to the fact that the eggs 

 are subjected to the injurious influences of the body fluid for intervals 

 varying with the time since maturation. 



When such eggs are placed in sea-water the physiologically different 

 groups of eggs are again affected very unequally. 



The totality of these varying influences produces marked variations 

 of a number of characters among the eggs of a given female, as well as 

 the eggs of different females. 



We have no direct or simple measure of the time since maturation of 

 the egg, nor of the physiological condition of the eggs. But one can 



x Eggs are ripe in this sense at the moment when germinal vesicle breaks down. 



