In this strobila form of Aurelia, it is easy to see 

 that what I now have to deal with is no longer an 

 individual organism, or true unit; it is instead a 

 string, or colony, of little jellyfishes, each jelly- 

 fish inverted according to its normal adult posi- 

 tion, and each attached to its fellow underneath 

 by the central part of its umbrella. 



Events now succeed one another rapidly. The 

 topmost unit, or, to call it by its proper name, 

 ephyrula, of every column is seized with an occa- 

 sional paroxysm and suddenly starts pulsating 

 more or less vigorously, after the manner of the 

 adult, seeming as if it were trying to tear itself 

 away from its anchorage to the others below. But 

 these early efforts are to no avail, for the contrac- 

 tions cease as suddenly as they begin. However, 

 the periods of quiescence become fewer and shorter 

 in duration. Eventually the young jellyfish settles 

 for good into a steady, unremitting pumping of its 

 disk; finally it breaks away — at last it starts its 

 long swim, upright after the fashion of its elders, 

 continuing thenceforward throughout its life and 

 without further interruption of the rhythmic move- 

 ments of its umbrella, like the tireless beating of 

 the human heart. 



[377] 



