On the Nervous Sy stein of Cassiopea Xamachana. 



137 



During the first 12 hours of an experiment, or as soon as the newly 

 regenerated tissue became recognizable, regeneration is more rapid 

 from the side on which the sense-organs are present. From that time 

 on, the regeneration from the two halves is (within the limits of error 

 of the measurements) about equal. The rate of regeneration of the 

 half-disk with sense-organs fails to equal that of the half-disk without 

 sense-organs. For both halves the rate was noticeably lower than that 

 of the inactive half of a disk in normal sea-water. The lack of proper 

 aeration commonly brought about through the pulsation of the active 

 half-disk may account in part for the lower rate of regeneration, but 

 there is unquestionably some more fundamental disturbance in the 

 metabolic activity caused by the presence of the excess of Mg ions in 

 the fluid. 



The results from experiments of this type with the halves of 40 disks 

 is given in table 2 and is shown graphically in figure 7. 



Table 2. — Record of experiments 12 and 13a {for 1 day to 9 days). 



[Forty disks each with insulated halves, one with sense-organs, the other without. Mg sea- 

 water. The letter C after tlie measurement for any day indicates that the central cavity 

 had been 611ed by the regenerated tissue.] 



