ACTIVATION OF UNFERTILIZED STARFISH EGGS. 



removal from the current the eggs return to their original shape. 

 Such eggs show a separation of fertilization-membranes in a 

 considerable proportion of cases, but not in all. In the experi- 

 ment just cited ca. 40 per cent, of the eggs exposed to the strong 



FIG. 2. 



current for if and 2 minutes showed well separated membranes 

 and a small proportion developed to the blastula stage. The 

 majority underwent disintegration inside the membrane without 

 development. 



Of twelve experiments performed with this method (with good 

 controls), using currents of densities ranging between 130 and 810 

 ma./cm., seven showed a varying degree of activation. Little or 

 no activation was obtained with currents of less than 300 ma./cm. 

 With higher intensities membrane-formation and activation 

 occurred in a minority of eggs; the strongest currents in addition 

 to deforming the eggs temporarily in the manner just described 

 had a marked destructive effect. 1 



In general the results of the foregoing experiments indicate that 

 the electric current has little activating effect upon the starfish 

 egg unless the intensities employed are sufficient to produce well 

 marked structural changes in the egg-system. The evidence of 

 these changes is deformation and subsequent breakdown of most 

 eggs. A certain proportion of eggs, however, recover and show 

 the usual phenomena of partial activation. These effects cannot 

 be referred to the observed rise of temperature which produces no 

 such definite deformation. Moreover, the highest temperatures 

 reached (30 31) require a much longer period of exposure for 

 activation of the degree observed. 



It should be remembered in considering the results of such 

 experiments that the physical conditions are far from constant, 

 and that the records of both temperature and current are subject 



1 This destructive action of strong currents on egg cells has been noted by other 

 observers; cf. the case of Crepidula as described by Conklin, Jour. Acad. Xat. 

 Sciences, Philadelphia, 1912, XV., p. 521. 



