18 



LEWIS R. CARY 



tion for each of the halves of a disk until the sense organs regained 

 their functional activity after which the half disk with sense 

 organs regenerated most rapidly, as in experiments of type 2, 



The results obtained in experiments with Mg solutions show 

 that there is an influence of the sense organs on the rate of re- 

 generation which is apparently exercised for a considerable time 

 after muscular activity has been suppressed. It was impos- 

 sible, however, by this method to differentiate with any cer- 

 tainty between the two effects, since there is no visual means of 



Fig. 8 To show the character of the operation in experiments of type 5. All 

 sense organs were removed from the disk. The two halves insulated by removal 

 of appropriate strips of subumbrella ectoderm. One half was kept in pulsation 

 by means of a circuit wave of contraction running through an endless labyrinth 

 of subumbrella tissue. 



ascertaining at what time the sense organs lose their power of 

 sending out the stimulus necessary for normal contraction. 



Since, as was shown by Mayer (op. cit), it is possible to main- 

 tain a circuit wave of contraction in the muscles of a half disk 

 without sense organs by making a series of cuts by which an end- 

 less labyrinth of subumbrella tissue is formed (fig. 8), the part 

 played by muscular activity and that by the stimuli from the 

 sense organs can be directly compared. 



In experiments of type 5 (fig. 8) all the sense organs were re- 

 moved from the medusa disks, the halves, insulated, and a circuit 

 wave of contraction started by an induction shock in the laby- 



