SEA-SALTS ABOUT ARBACIA EGGS. 



181 



c.c. of eggs removes one third as much as in three. On the 

 basis of these assumptions and the actual titrations, we can con- 

 struct a curve showing the comparative amounts of chlorine 

 which, under the conditions imagined, I c.c. of eggs would ab- 

 stract from i c.c. of sea-water in one hour, if the rate of removal 

 for that hour were constantly the rate deducible from the de- 

 terminations actually made after exposures of 15, 60, 90, 120, 

 150, and 1 80 minutes. 



Milligrams 

 Chlorine 

 removed 



from 

 i cc. jea- 

 water in 

 one hour 

 at rate 

 found at 



(1, 



(3) 



Minutes 



FIG. i. Curve showing gradual loss in the power of eggs to abstract salts 

 from sea-water. 



The number of titrations upon which the points indicated in the 

 curve rest, is given in brackets. Clearly there is a steady ap- 

 proach to zero. Since the rate of chlorine removal by eggs im- 

 mersed for 180 minutes falls from the height which it had reached 

 after 15 minutes it follows that the process of salt-abstraction is 

 reversible. However, there is no equilibrium. We must suppose 

 therefore that the chlorine-removing mechanism slowly breaks 

 down. 



Within the time-limit of these experiments, the only part of 

 the egg-system known to undergo dissolution is the jelly which 

 surrounds each newly shed egg. This chorion disintegrates 

 slowly in sea-water. Fortunately it can also be readily removed 

 by moderate shaking. I therefore compared the chlorine deficits 

 produced by equal volumes of normal and dechorionized eggs in 

 equal volumes of sea-water. 



The experiment, of course, involves two errors : in the first 

 place one cannot be certain that the jelly has actually been re- 

 moved from every egg; and secondly, its removal from a con- 

 siderable number renders it certain that a given volume of 

 dechorionized ova will contain a larger number of cells than an 



