58 SEA-SIDE STUDIES. 



the exquisite fringe of tentacles which hangs from the 

 border of the disc, I observed every one of these polyp- 

 like tentacles move to and fro, now protruded, now with- 

 dra^ATi into the substance of the disc, each with indepen- 

 dent action, and this on a portion of the disc which had 

 been many hours separated from the animal. The fringe 

 does no more when the animal is vigorous on the warm 

 surface of the tranquil sea ; it does no less now that the 

 animal is in shreds. Look in that saucer, and you will 

 observe the fragment of another Medusa ; the animal is 

 dead, and almost melted away. I have already cut out two 

 of the ovarial chambers, yet you see the oval tentacles are 

 twisting about as if seeking prey. Tliis is not ciliarity, but 

 contractility. This is life, unless you restrict the tenn life 

 to the meaning it carries in its highest formula. If it is 

 motion, it is vital motion. 



Can motion, alone, be taken as the index of life ? Cer- 

 tainly not. But let us try to be precise in our language. 

 Life is a complex term, indicating complex phenomena. In 

 its highest formula, expressing all the requisite generality of 

 what is included in the term, it indicates the triple unity 

 of Nutrition, Reproduction, and Decay. An animal grows, 

 reproduces, and dies ; these are the three capital and cardinal 

 facts of its organism. Out of these issue many derivative 

 and secondary phenomena, one of which is Motion. In 

 some animals, motion can scarcely be said to have any 

 existence. The Ascidians, for example, although of rather 

 complex structure, have nothing which approaches it, unless 

 we should so designate the occasional contraction and dila- 



