APPENDIX 419 



clieerfully in the water like an independent and uninjured 

 animal, but the central piece seemed dead. When from an 

 entire specimen I cut out all the marginal organs except one, 

 the animal went on moving as if it were perfectly uninjured ; 

 but if I cut away all the marginal bodies, the animal seemed 

 dead, no longer moved. 



If one carefully observes how the uninjured animal moves 

 in the water, he will notice that the motion starts always 

 from one of the marginal bodies and spreads in various direc- 

 tions as if it were propagated through telegraph wires. But 

 at one moment the motion begins at this organ, the next at 

 another, the next again at another. 



Where then are we to look for the individual in such an 

 animal ? It is not an indivisible whole, but a divisible, and 

 divisible into so many parts. But neither can we describe 

 the smallest part of the whole which is capable of life as an 

 individual, for such a part cannot continue its independent 

 life indefinitely, it perishes after a time. 



If we compare these phenomena with those which I have 

 described in the case of the worm we see a difference. In 

 the latter case we also obtain by section a part capable of 

 independent life, but it only remains an individual for a 

 moment ; immediately afterwards it begins to develop again 

 into an entire worm, which does not happen in the jelly-fish. 



But to proceed further. When I made a jelly-fish motion- 

 less and then kept it in conditions favourable to life in pure 

 sea-water, then after a time, at some spot or other on the 

 summit, twitchings appeared ; these movements extended to 

 wider and wider areas, became more rapid and vigorous, and 

 after a time a regular pulsation was re-established in the 

 mutilated animal — it continued to live. Thus a new centre of 

 life has arisen at some point in the animal, and this new 

 centre now accomplishes the movements of the whole — a most 

 marvellous phenomenon, which, however, is explained by the 



