RALPH S. LILLIE 785 



In both Asterias and Arhacia exposure of the eggs to the pure 

 NaCl solution for a few minutes alters the consistency of the cell 

 surface, and apparently also the permeability of the plasma mem- 

 brane, in a highly characteristic manner. The eggs cohere in small 

 clumps, or agglutinate; this effect is well marked even in eggs exposed 

 to the pure NaCl solution in a finger-bowl without any centrifuging, 

 but the latter process promotes the formation of larger and firmer 

 aggregates. This agglutination, although accompanying the removal 

 of the jelly, is an entirely independent process, and like the removal 

 of the jelly is prevented by the presence of calcium in the solution. 

 A further characteristic effect produced by the pure NaCl solution 

 in Asterias eggs (but not in Arhacia) is the formation of apparently 

 normal fertilization membranes in a certain proportion of eggs; and 

 in some cases cleavage and development to a blastula stage result. - 

 This membrane-forming and activating effect is also antagonized 

 by calcium.^ 



The solution of the jelly in pure NaCl solution is a somewhat 

 gradual process; the jelly gradually incorporates water, and swells, 

 eventually losing coherence and passing into solution. The process 

 of swelling miay be arrested at any stage by returning to sea water; 

 but there is no evidence of reversal in the sense of a return of the 

 jelly to its original water content. Eggs were placed in a finger- 

 bowl, the sea water removed as far as possible, and to the remaining 

 mass of eggs (about 1 cc.) 100 cc. of 0.54 NaCl were added. From 

 the NaCl solution eggs were returned to finger-bowls containing sea 



2 Lillie, R. S., Am. J. Physiol, 1910, xxvi, 106; cf. 119. 



^Lillie, R. S., Am. J. Physiol, 1910-11, xxvii, 289. A further interesting 

 effect of the pure isotonic NaCl solution, also antagonized by CaClo, is that it 

 prevents the dissolution of the germinal vesicle, and hence the maturation pro- 

 cess, in starfish eggs placed in the solution immediately after removal from the 

 animal. If such eggs are left in the pure NaCl solution for from 5 to 10 minutes, 

 and are then returned to sea water, they remain permanently immature. Simi- 

 lar treatment with a calcium-containing NaCl solution (e.g., 95 volumes of m /2 

 NaCl plus 5 volumes of m /2 CaCl2) leaves them apparently unaffected. The pure 

 NiCl solution thus produces the same effect as weak fatty acid solution or high 

 temperature, either of which, if applied at this time, also prevents maturation 

 (cf. Lillie, R. S., Biol Bull, 1917, xxxii, 135). Mineral acids appear to have a 

 similar effect (cf. Loeb, J., Arch. ges. Physiol, 1902, xciii, 59). 



