On the Nervous System of Cassiopea Xamachana. 



135 



The results from the 40 disks recorded in table 1 are shown in figure 

 6, in which the divisions along the abscissa show the time of regenera- 

 tion in days, those along ordinate the amount of regeneration measured 

 in millimeters. The record for each specimen is carried to the time of 

 closure of the open circle in the center of the disk by the sheet of 

 regenerated tissue. 



From the start of regenera- 

 tion the new tissue produced 

 from the side with its sense- 

 organs intact is shown to be 

 more rapid. In the early 

 stage of regeneration this 

 difference is more striking 

 upon a cursory examination 

 than in the later stages, al- 

 though the actual difference 

 on the rate of growth of 

 new tissue changes only 

 slightly during the entire 

 period of regeneration. The 

 proportion between the 

 amounts of new tissue 

 formed each day, taking the 

 amount regenerated from 

 the side without sense- 

 organs as the unit, was re- 

 spectively : First day 1 : 1 .53 ; 

 second day 1:1.44; third 

 day 1:1.41; fourth day 

 1:1.38; fifth day 1:1.39. 



The regeneration from the 

 half without sense-organs is 

 more regular, as is shown by 

 the fact that for the mean of 



each day's observation the Fig. 6.— showing relative rates of regeneration of the 



T^rrkhoKlo t^rrnr i<5 lpsi«5 for halves of 40 disks. The upper line represents the 



prOOaOie error Ib lebb lUl half-diskswith sense-organs, the lower line represents 



that half than for the one those without sense-organs. 



upon which the sense-organs 



remain. This result would be expected to follow from the fact that 

 the inactive side was reUeved from the influence of the marginal sense- 

 organs, which would introduce many stimuli of varying intensity, all of 

 which would have either a retarding or accelerating influence upon the 

 processes of regeneration. 



When the rates of regeneration of certain disks in table 1 are com- 

 pared with one another, the cause of the uncertainty of the results 

 obtained in experiments with entire disks is clearly shown. The 



