638 



SCIENCE 



[N. S. Vol. XXXVI. No. 932 



the exception of the heavy metals) caused them 

 to live and form an embryo.^ Seven years ago 

 he formulated the hypothesis that this antag- 

 onistic action of salt was primarily due to the 

 fact that the solution of only one salt in a, 

 sufficiently high concentration alters the mem- 

 brane of the cells, thereby increasing its per- 

 meability, vchile this increase can be inhibited 

 through the addition of the antagonistic salt." 

 In a recent paper a summary of the facts sup- 

 porting this hypothesis was giren.^ Accord- 

 ing to this hjrpothesis, the pure ISTaCl solution 

 slowly increases the permeability of the mem- 

 brane, diffuses into the egg and kills the germ, 

 while the addition of a small amount of 

 MgCl,, CaCL, SrCl, BaCl,, etc., inhibits or 

 retards this increase of the permeability and 

 the death of the embryo. During the last year 

 Osterhout has published confirmatory experi- 

 ments on Laminaria. 



This summer the writer has found a new 

 method by which it was possible to test the 

 validity of this hypothesis for the egg of 

 Fundulus. This egg has a considerably higher 

 specific gravity than sea water. It will float 

 in a 12/8 m NaCl solution but not in a 11/8 

 m NaCl solution. The method consisted in 

 putting the eggs into solutions of a higher 

 specific gravity than that of a 12/8 m NaCl 

 solution and observing how long they will float 

 in such a solution. For these experiments eggs 

 were used which had been fertilized at least 

 three or four days previously. The following 

 striking facts were found. If the eggs are 

 put into a 3 m solution of NaCl they will float, 

 but as a rule not longer than three hours. 

 Then they will sink to the bottom of the test 

 tube. Before sinking they lose water as is 

 indicated by the collapse of the membrane and 

 the shrinking of the yolk sac. Probably some 

 NaCl enters into the egg. When we put 

 eggs into a 10/8 m solution of CaCl^ they 

 float at flrst, but will sink in about 1/2 hour. 

 If we use CaCl, solutions of a still higher con- 

 centration the eggs will shrink and fall to the 



^Pfluger's ArcUv, 88, 68, 1901; Am. Jour, of 

 Physiology, 6, 411, 1902. 



^Pfluger's Archiv, 107, 252, 1905. 

 » Science, 34, 653, 1911. 



bottom just as fast or still faster. If, how- 

 ever, we put the eggs into a mixture of 50 c.c. 

 3 m NaCl 4-2 c.c. 10/8 m CaCl, they will 

 float three days or longer at the surface of 

 the solution. During this time the eggs do not 

 shrink at all or very little and the embryo 

 keeps alive. In a mixture of 50 c.c. 2 1/2 m 

 NaCl.+ 1 c.c. 2 1/2 m KC1+ 0.75 c.c. 2 1/2 m 

 CaCl, some of the eggs floated on the surface 

 as long as ten days, while in a 2 1/2 m solu- 

 tion of NaCl they did not float more than a 

 few hours. The only possible explanation of 

 these experiments is that the membrane of the 

 eggs of Fundulus is practically impermeable 

 to water and to salts in a physiologically bal- 

 anced solution. If the egg, however, is trans- 

 ferred to a hypertonic non-balanced solution 

 the natural impermeability of the membrane 

 is gradually lost and water will diffuse out of 

 the egg and its specific gravity increase to 

 such an extent that the egg sinks. 



When the eggs are put into pure solutions 

 of each of the following salts, MgClj, SrCl,, 

 BaCl,, above a density of 1.0634 the eggs will 

 float at first but will shrink and fall to the 

 bottom in less than an hour; the sinking be- 

 gins the more rapidly the higher the concen- 

 tration. This indicates that the higher the 

 concentration the more rapidly does the salt 

 increase the permeability of the membrane for 

 water. If, however, a small but definite 

 amount of any of these salts is added to 50 c.c. 

 3 m NaCl the eggs will float on the 3 m NaCl 

 solution for a considerably longer time than 

 if no salt with a bivalent metal is added. 

 These experiments show that the toxic or in- 

 jurious action of the pure NaCl solution ob- 

 served in my experiments on the Fundulus 

 egg was due to an annihilation of the specific 

 impermeability of the membrane of the egg 

 through the action of NaCl and the subsequent 

 entrance of this salt into the egg, and that the 

 antagonistic action of the salts with bivalent 

 metals was due to the fact that they inhibited 

 the increase of permeability of the membrane 

 for salt and water. 



2. In 1899 the writer published the fact that 

 the addition of a sufficient amount of acid 

 causes the muscle of a frog to swell in an 



