1 68 Charles R. Siockard 



had stopped beating, within fifteen minutes, the eggs were returned 

 to sea-water; thirty-five minutes later one heart was contracting 

 ahnost normally, while another was beginning feebly, the others 

 had not recovered even after an hour. On examining the seven 

 embryos the following morning all had entirely recovered. The 

 result demonstrates the readiness with which salts permeate the 

 membrane in eggs a few days old. 



In 1903 Brown recorded the results of experiments, showing the 

 immunity of Fundulus eggs and embryos to electrical stimulation. 

 For these experiments he used eggs at various stages but some were 

 tried when in the two-cell stage. These experiments, as Brown 

 concluded, go to show the permeability of the membrane during 

 the first hours of development. He states that the most probable 

 explanation of the immunity of these eggs to electric currents as 

 well as to osmotic changes of the medium in which they live is 

 that the membranes of the egg are so freely permeable to ions 

 and possibly to neutral particles that no polarization can occur. 

 "There is a gradual increase in susceptibility to osmotic changes 

 and to the electric current as the embryo develops, the adult being 

 readily stimulated by the current from a single cell, which is quite 

 without action in the embryo." 



With the above results and interpretations in view. Brown ('05) 

 has since, from far less convincing experiments, arrived at opposite 

 conclusions. He claims now that the membrane of Fundulus 

 eggs is practically impermeable to salts and water during the first 

 six or eight hours of development; since eggs placed in distilled 

 water do not lose their salts during that period. It would be sur- 

 prising if these eggs did lose their salts in distilled water as they are 

 capable of normal development in this medium. Very probably 

 the inorganic salts of this egg are held in combination in the proto- 

 plasm so that they are not able to diffuse out in hypotonic solutions 

 and the readiness with which the membrane is penetrated makes 

 the osmotic pressure low. The fact that the conductivity of the 

 distilled water containing the eggs increased after the first eight 

 hours is probably due to an excretion from the eggs. They 

 undoubtedly give off some waste products as an odor is often ob- 

 served when a bowl containing eggs is uncovered after standing 

 overnight. 



