418 



APPENDIX 



When I divided one of these animals into two halves by 

 an incision passing through the summit, each half went on 

 swimming independently. It must be borne in mind that 

 the locomotion of the large jelly-fishes is produced by 

 dilation and contraction of the umbrella. Then I cut the 

 animal into four, then into eight parts ; I could cut it into as 

 many parts as there were marginal bodies — and each separate 

 piece endeavoured to go on moving independently. 



When I took one of these pieces — a radius of the whole 

 creature — and cut off pieces from this radius, each piece when 



FiCx. 5. 



Fig. G. 



separated was dead and motionless if it did not contain the 

 small body on the margin, the so-called marginal sense-organ. 

 But the smallest piece containing this organ continued to 

 move, pulsated rhythmically in a perfectly constant manner, 

 somewhat as the heart of a frog when dissected out from the 

 body. A prick with a needle in a particular part of the 

 marginal organ, and the motion in this small portion also 

 ceased. In this organ then was the starting-point of the 

 motion, here was the nerve-centre. 



W^hen I cut out the central portion of the umbrella so 

 that only the margin was left, the latter went on moving quite 



