14 LEWIS R. CARY 



entirely to the muscular tissues, while the nervous network is 

 still capable of transmitting the impulse necessary for pulsation 

 over an area submerged in the magnesium solution where no 

 contraction of the muscles could be observed. When kept in 

 the magnesium sea water for a prolonged period the sense organs 

 become incapable of giving rise to the stimulus necessary for 

 normal pulsation long before the nervous network loses its capac- 

 ity for transmitting such a stimulus, so that a ring cut from a 

 medusa disk and activated by a circuit wave of contraction will 

 show by an indicator strip in sea water (Mayer, I.e., page 122) 

 the transmission of the nervous impulse for a considerable time 

 after a ring that retains its sense organs is no longer able to acti- 

 vate its indicator strip. 



When medusa disks prepared with insulted active and inactive 

 halves are put into the magnesium sea water they lose their 

 power of muscular movement within a few moments. Usually 

 all of the disks float on the surface of the new solution for from 

 twenty minutes to a half hour before they become adjusted to 

 the abnormally dense medium. At the end of this period they 

 settle to the bottom of the jar and remain completely relaxed 

 throughout the experiment. 



During the first twelve hom^s 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 is (within the limits of error 

 of the measurements) about equal from the two halves. The 

 rate of regeneration of the half disks with sense organs falls to 

 equal that of the half 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. 



Experiments with chloroform and with KCN dissolved in sea 

 water did not give satisfactory results. In both these solutions 

 the tissues of the medusa underwent rapid disintegration if the 



