On the Nervous System of Cassiopea Xamachana. 



145 



There was noticeable an indefinite sort of rhythm in the rate of 

 pulsation, as if the sense-organ underwent periods of fatigue from which 

 it was enabled to recover after having given off the stimuli for pulsation 

 for a time at a rate considerably lower than that observed previous to 

 the removal of the other centers. Those periods of depression in the 

 pulsation-rate were of such 

 short duration that they 

 could not be distinguished 

 in the amount of tissue 

 regenerated, if, as would 

 seem probable, the sense- 

 organs were affecting other 

 metabolic activities in a 

 similar manner. 



In all experiments of this 

 type the results were of the 

 same nature as in those 

 when the sense-organs on 

 the activated half-disks had 

 not been disturbed. The 

 amount of time necessary 

 to bring about the closing 

 of the cavity in which re- 

 generation was measured 

 was not sufficiently different 

 from that in specimens 

 where the active half-disk 

 retained its sense-organs to 

 indicate any serious distur- 

 bance in metabolic activity. 

 The different specimens in 

 these, as in the previous 

 series, showed great varia- 

 tions in physiological 

 activity (see tables 1, 2, 3, 

 and 4), but there was noth- 

 ing strikingly characteristic about the behavior of the specimens with 

 a single sense-organ. 



EFFECT OF TIME INTERVAL BETWEEN SEPARATION OF DISKS INTO 

 HALVES AND REMOVAL OF SENSE-ORGANS. 



In all the experiments on regeneration involving half-disks which 

 retained their sense-organs it was noticeable that the difference in 

 rate of regeneration from the two halves was most marked during 



FIG. 9. Showing rates of regeneration of active and 

 activated half-disks. The divisions along the ordi- 

 nate represent regeneration in millimeters; those 

 along the abscissa represent time in days, i 



