EFFECT OF IONS UPON TISSUE 



569 



effect is much more marked during the first twenty-four 

 hours of development than during the later stages. 



Everyone who has had experience with the effects of 

 KC1 upon the contraction of muscles knows how poisonous a 

 pure KC1 solution is. I was much surprised to find that a -f-n 

 KC1 solution is even less harmful to the newly fertilized egg 

 of Fundulus than a -f- n NaCl solution. More eggs develop 

 in the former than in the latter solution. The following 

 table gives a clear illustration of this condition : Mixtures of 

 -f-n NaCl and f n KC1 solutions were used. Each solution 

 had about seventy to eighty eggs. The percentage of eggs 

 that formed embryos is indicated for each solution. 



TABLE I 



It is evident that if the number of K ions is greater than 

 the number of Na ions, the percentage of eggs which are 

 able to develop is larger. It is remarkable that in a solu- 

 tion of 98 NaCl 4- 2 KC1 fewer eggs from an embryo than 

 in 95 NaCl 4- 5 KC1 or in 90 NaCl 4- 10 KC1, although in 

 these last two solutions the amount of KC1 is far in excess 

 of that in sea- water. Hence we are forced to conclude that 

 K ions are less poisonous for the earlier stages of Fundulus 

 than Na ions. It is better for the egg that K ions enter 

 into combination with the proteids of the protoplasm than 

 Na ions. 



