PHYSIOLOGY: J. LOEB 
513 
effect' upon the membrane can best be studied in experiments on the 
recovery of eggs previously poisoned with KCl. Eggs were put directly 
from sea water into m/2 KCl for twelve hours. These eggs must have 
contained an excess of KCl, since in this solution all the hearts of un- 
washed eggs stop beating in less than two hours. The heartbeat was 
resumed when enough KCl had left the eggs after they had been trans- 
ferred into the proper solutions. The resumption of the heartbeat 
became, therefore, an indicator for the rapidity of diffusion of the KCl 
from the heart into the membrane or the surrounding solution. Since 
the concentration of KCl was approximately equal in each egg at the 
beginning of the experiment, the differences in time required for recovery 
were due to the influence of the outside solution upon the rapidity of the 
diffusion of KCl from the egg into the membrane. Table I shows the 
percentage of hearts which recovered from the effects of KCl in various 
salts of Na, NH4, and Mg in twenty-four hours. It is obvious that 
beginning with a limiting lower concentration all the hearts were beating 
again at that time in all the solutions, although most of the solutions 
are so poisonous that they would have killed the embryo in a short time 
had they been able to diffuse in more than traces into the egg. They 
acted by bringing about a certain modification of the membrane render- 
ing possible the diffusion of the potassium salts. 
TABLE 1 
PERCENTAGE OF HEARTS RECOVERING FROM POTASSIUM STANDSTILL 
IN TWENTY-FOURS IN 
00 
0 
r-i 
CO 
<t 
c> 
<M 
■<* 
10 
1 
0 
1* 
i 
\ 
s 
0 
W 
Sea water 
100 
100 
91 
60 
50 
26 
15 
45 
15 
10 
25 
35 
5 
NaCl -f- CaCl2 
100 
95 
100 
90 
55 
55 
25 
25 
5 
5 
10 
NaCl 
100 
100 
100 
100 
100 
90 
40 
25 
15 
10 
5 
NaBr 
100 
100 
100 
100 
90 
75 
66 
50 
35 
30 
40 
5 
NaNOs 
100 
100 
70 
35 
15 
10 
15 
10 
0 
10 
5 
Nasacetate 
100 
100 
100 
100 
100 
85 
35 
15 
0 
5 
5 
0 
5 
NaaSO^ 
100 
100 
100 
100 
90 
93 
90 
81 
38 
14 
5 
NaHCO., 
100 
100 
100 
100 
75 
35 
10 
5 
NaaCOs 
35 
30 
20 
20 
5 
5 
NajHPO^ 
95 
100 
90 
55 
50 
25 
10 
14 
5 
0 
Nag citrate 
95 
60 
80 
30 
20 
NH4CI 
38 
72 
89 
83 
77 
41 
16 
15 
15 
11 
(NH4)2S04 
45 
75 
70 
75 
65 
65 
50 
31 
15 
10 
30 
10 
(NH4)3 citrate 
80 
68 
55 
25 
14 
MgCl2 
100 
85 
95 
75 
55 
25 
25 
25 
15 
10 
0 
5 
MgS04 
100 
95 
70 
95 
90 
80 
45 
70 
30 
10 
10 
15 
