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 
KCl upon the contraction of muscles knows how poisonous a 
pure KCl solution is. I was much surprised to find that a 5n 
KCI solution is even less harmful to the newly fertilized egg 
of Fundulus than a $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 
$n NaCl and $n KCl solutions were used. Each solution 
had about seventy to eighty eggs. The percentage of eggs 
that formed embryos is indicated for each solution. 
TABLE I 
Percentage 
Character of Solution of Eggs That 
Formed Embryos 
Lissaamantess 98 c.c.$nNaCl+ 2c.c.§n KCl 6% 
Ohare ate as 95 “ + £55 «“ 10 
Dasok wastedask 90 aS + 10 58 25 
a ee 60 st + 40 a 30 
tv eiuee eames 40 “ + 60 “ 40 
| Ee tee 10 “ + 90 “ 33 
[REE eas 5 “ + 95 “ 33 
Biidiea naiedtes 2 34 + 98 a 33 
Oeeiicar ateace 0 s + 100 & 38 
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 +2 KCl fewer eggs from an embryo than 
in 95 NaCl +5 KCl or in 90 NaCl+10 KCl, although in 
these last two solutions the amount of KCl 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. 
Digitized by Microsoft® 
