SEA-SALTS ABOUT ARBACIA EGGS. 



179 



order to prevent the loss of good material through premature 

 shedding of the eggs and sperm. 6 



With these precautions the titration of the chlorides yields 

 perfectly consistent results. 



Considering the sources of error and especially the difficulty of 

 measuring the volume of a large number of eggs, the constancy 

 in the sense of these differences is impressive. There is unques- 

 tionably a chlorine-deficit in egg-secretion. 



IV. THE ORIGIN OF THE CHLORINE-DEFICIT. 



How does the chlorine deficiency arise? There is a presump- 

 tion in favor of attributing it to the eggs;, on the other hand, if 

 these eliminate substances capable of masking the chlorine, AgNO 3 

 would give no more clue to its presence than in the titration of 

 chloroform or trichloracetic acid. The problem is soluble by 

 two very simple tests. 



If the chlorine is removed by the eggs rather than masked by 

 the exudates, it should be possible to prepare egg-secretions with- 

 out a chlorine-deficit. To accomplish this the eggs should be 

 exposed to sea-water until all the chlorine which they are able 

 to hold has presumably been taken up. Such eggs if subsequently 

 permitted to secrete into a fresh volume of sea-water should re- 

 move no chlorine whatever on their second exposure. 



The reasoning is justified by the following experiment in which 

 i c.c. of control sea-water, i c.c. of first sea-water and i c.c. of 

 second, are all expressed in terms of AgNO 3 w/2O. 



TABLE III. 



6 The efficacy of a three- to five-minute submersal in fresh water was first 

 noticed by my colleague, Miss Sampson. 



