EFFECT OF IONS UPON TISSUE 575 



stages of the development of the Funduhis egg occur in a 

 normal way. The fact that such a solution does not contain 

 any Na ions raises the question whether the main importance 

 of ions in these phenomena does not lie in the influence they 

 have upon the physical qualities of the protoplasm (absorp- 

 tion of liquids, state of matter, etc.) If this were the case, 

 we might easily understand that various mixtures of ions 

 might bring about the same effect upon -tissues, provided 

 that they affect the physical qualities of the protoplasm in 

 the same manner. In the next paper we shall show that the 

 esffifs of the sea-urchin can reach the blastula stage in a 



oo o 



mixture of l ^n MgCl 2 and *g-n CaCl 2 . But each of these 

 vicarious mixtures serves only for a certain class of vital 

 processes, while a mixture of NaCl with a small amount of 

 Ca and K ions allows the whole cycle of life phenomena 

 (with certain exceptions) to be completed. 



5. Herbst 1 has tried to prove that practically every sub- 

 stance contained in the sea-water is necessary for the devel- 

 opment of the egg of the sea-urchin. His proof consisted 

 chiefly in removing one of the constituents of the sea- water, 

 and showing that in such modified sea-water the eggs were 

 not able to develop. This method does not warrant the con- 

 clusions Herbst has drawn from them. In a solution of 96 

 c.c. fn NaCl + 2 c.c. Y CaCl 2 + 2 c.c. f-ra KC1 all the Fun- 

 dulus eggs develop and hatch. If we remove the Ca ions, 

 the majority of Fundulus eggs cannot develop, and of the 

 few that develop none hatch. According to Herbst it would 

 follow that the surrounding medium must contain Ca ions 

 for the development and hatching of the Fundulus eggs. 

 Yet we have seen that the Fundulus egg develops and 

 hatches in distilled water. Ca ions become a necessity only 

 if the surrounding solution contains Na ions in excessive 

 quantities. 



1 HEKBST, Archivfiir Entwickelungsmechanik, Vol. V (1897), p. 649. 



