THE GROWTH OF JELLY-FISHES. 



58s 



tory is not a simple process of growth, nor a metamorpliosis, like 

 that which occurs among insects. 



The caterpillar, which hatches from the butterfly's q^^, is per- 

 haps as unlike the butterfly as the hydra is unlike the jelly-fish, 

 but it never loses its 

 identity, and the individ- 

 ual which hatches from 

 the Qgg is the same one 

 which passes through all 

 the caterpillar molts, be- 

 comes a chrysalis, and 

 finally escapes as a per- 

 fect butterfly, just as 

 the chick which hatches 

 from a hen's <d^g is the 

 individual which finally 

 becomes a hen and lays 

 eggs in her turn. The 

 growth of the butterfly 

 is accompanied by great 

 and sudden changes 

 from one stage of devel- 

 opment to another, but 

 it is simply a process 

 of growth and develop- 

 ment, while the life of 

 Dysmorphosa is quite 

 different. The planula, 

 which hatches from the 

 Q^^, becomes metamor- 

 phosed into a root, just 

 as the caterpillar becomes changed into a chrysalis ; but here the 

 resemblance stops, for the root goes no further, and it may still 

 remain a root after numbers of jelly-fishes have grown up, laid 

 their eggs, founded new colonies, and died. The feeding hydras 

 and defensive hydras never grow up into jelly-fish, but, as long as 

 they live, continue to perform their proper parts in the colony, 

 and this is equally true of the blastostyles, for these do not become 

 jelly-fish ; they simply produce jelly-fish buds, and each one may 

 persist as a blastostyle and continue the process of budding long 

 after the younger buds have completed their history. 



In all these particulars the life of Dysmorphosa is a great de- 

 parture from the normal life-history of animals, for, as a rule, 

 each embryo which hatches from an Qg^ is destined to become an 

 adult animal, and only one. 



The simpler aspects of the phenomena of life are older or more 



Fig. 4, a section, and Fig. 5, a surface view of the larva of 

 Liriope, to show the formation of tlie mouth, e, and the 

 stomach, d. 



