CHAPTER IX. 



AcALEPHiE {Sea-blubbers). 



Continued. 



We propose now to speak of the reproduction of the 

 Medusae, at least of the Discophora, or umbrelliform fami- 

 lies, for of the other orders we know little, except their 

 forms. Some of the phenomena of Alternate Generation 

 have been described in a previous paper, a compound hy- 

 droid Polype giving birth to tiny Medusae, which after- 

 wards produce a generation of Polypes. We have now to 

 contemplate the counterpart of this wonderful process, — a 

 free swimming Medusa producing gemmules, or motive 

 eggs, each of which becomes a stationary Polype, and ulti- 

 mately throws off a number of Medusae. 



The ovaries in these animals are ordinarily placed in 

 contact with the walls of the central stomach, or with the 

 digestive canals that radiate from it across the disk. At the 

 season of development they consist of numerous ribands 

 of membrane, much folded and convoluted, and fringed 

 "with free pendent filaments, covered with vibratory cilia. 

 The ova are globose, gelatinous germs, existing in immense 

 multitudes, which on extrusion are strongly ciliated, and 

 bear a close resemblance to Infusorial Animalcules. They 



