290 



F. W. Bancroft. 



in various ways and placing the pieces in a trough of sea water 

 through which the galvanic current was conducted with non-polar- 

 izable electrodes. The current strength varied from 25 to 200 'J. 

 The responses were usually distinct with 25 '^, but became more de- 

 cided as the current was increased. 



If a meridional strip passing from the edge on one side through 

 center of the bell to the other edge be prepared and the current 

 passed through it transversely, tentacles and manubrium turn and 

 point towards the cathode (Fig. I) . A reversal of the current in- 



r^ 



+ 



Fig. I. 



itiates a turning of these organs in the opposite direction, which 

 is usually completed in a few seconds. This can be repeated many 

 times and the tentacles continue to respond after hours of ac- 

 tivity. The manubrium, however, tires sooner and fails to re- 

 spond. If the strip is placed with its subumbrellar surface up- 

 wards and extended in a straight line parallel to the current lines 

 the making of the current causes the tentacles at the anode end to 



-h 



Fig. 2. 



turn through an angle of 180 degrees and point towards the 

 cathode. The tentacles at the cathode end become more crowded 

 together, reminding one of the tip of a moistened paint brush, 

 and also point more directly towards the cathode (Fig. 2) . The 

 experiment may be varied in still other ways by cutting smaller 

 or larger pieces from the edge of the swimming bell, but the re- 

 sponse is always the same. The tentacles wherever possible, and 

 to a less extent, the manubrium, bend so as to point towards the 



