110 



THE BEAUTIES OF NATURE 



CHAP. 



At the same time transverse wrinkles (4) 

 are formed round the body, first near the 

 free extremity and then gradually descend- 

 ing. They become deeper and deeper, and 

 develop lobes or divisions one under the other, 



Fig. 5. Medusa aurita, and progressive stages of development. 



as at 5. After a while the top ring (and 

 subsequently the others one by one) detaches 

 itself, swims away, and gradually develops 

 into a Medusa (6). Thus, then, the life-his- 

 tory is very similar to that of the Hydroids, 

 only that while in the Hydroids the fixed 

 condition is the more permanent, and the free 



