44 E. E. JUST. 



Against these observations the objection might be raised that 

 the failure of washed eggs to form membranes in greater number 

 is simply due to the low concentration of butyric acid in sea- 

 water since from the washed eggs all the water cannot be removed. 

 Against this we have (i) the fact that dry eggs quickly washed 

 once or twice may give one hundred per cent, membranes. 

 If, by chance, body fluid was present with shed eggs they were 

 always washed. (2) After washing all but a negligible amount of 

 water can be removed. (3) Diminution in concentration of acid 

 does not explain absolute loss by the egg of the power to respond 

 to butyric acid which may take place in an hour. (4) Finally, 

 washed eggs subjected to butyric acid in higher concentration 

 (e. g., 3 c.c. n/io butyric plus 50 c.c. of sea-water) if they form 

 membranes at all form the thick closely adherent membranes 

 which result from exposure to too great concentration. Washing 

 alone is responsible for the failure of the eggs to form membranes; 

 repeated washings in 10 to 15 c.c. of sea-water for one to two 

 hours or a single washing in 250 c.c. 1 will render eggs incapable 

 of activation by butyric. 2 



2. Effect of Body Fluid. My 1914 experiments on the initia- 

 tion of development of Nereis eggs through increased temperature 

 proved that serum as definitely inhibits initiation of develop- 

 ment, as it does fertilization (Just, '15). I was, therefore, led 

 to study the effects of Echinarachnius body fluid on butyric acid 

 activation of Echinarachnius eggs. Eggs mixed with body fluid 

 form few if any full membranes; they usually form the thick 

 closely adherent type of membrane. 



(a) Thus, the eggs of Lot C of July 26 mentioned on page 43 

 (eggs plus two drops of body juice) gave the following: 



Exposure in seconds 20 25 30 35 40 60 



Per cent, of membranes o 3 14 16 n o 



(b) July 15, 10:30 A.M. Eggs plus body fluid (2 drops each) 

 in butyric acid sea-water for 20, 25, 30, 35 and 40 seconds. 



10:50 A.M. Not, one full membrane; some eggs have the thick 

 contracted membranes. 



1 I did not wash in the larger quantities often, for with them the difficulty of 

 recovering the small number of eggs increases; moreover, concentrating the eggs 

 takes time thus introducing another factor. 



~ Washing may not have the same effect on Arbacla eggs which are much more 

 resistant. (See Just, 



