DEVELOPMENT OF MEDUS.E FROM POLYPES. 



545 



Fig. 279. 



of coins ; a sort of fleshy bulb, somewhat of the form of the original 

 Polype, being still left at the attached extremity (Fig. 279, a). 

 The number of circles is indefinite, and all are not formed at 

 once, new constrictions appearing below, after the upper portions 

 have been de- 

 tached ; as many 

 as 30 or even 40 

 have thus been 

 produced in one 

 specimen. The con- 

 strictions then gra- 

 dually deepen, so 

 as to divide the 

 cylinder into a 

 pile of saucer-like 

 bodies; the divi- 

 sion being most 

 complete above, 

 and the upper disks 

 usually presenting 

 some increase in 

 diameter : and 

 whilst this is 

 taking place, the 

 edges of the disks 

 become divided 

 into lobes (b), each 

 lobe soon present- 

 ing the cleft with 

 the supposed rudi- 

 mentary Eye (more 

 probably an Audi- 

 tory organ) at the 

 bottom of it, which 

 is to be plainly 

 seen in the de- 

 tached Medusae 

 (Fig. 280, c). Up 

 to this period, the 



tentacles of the ori- Successive Stages of Development of Medusa- 

 gmal Polype sur- buds from Strobila-larva :—a, Polype-body ; 6, its 

 mount the highest original circle of Tentacles ; c, its secondary circle 

 nf +Via dioVo . k + °f Tentacles ; d, proboscis of most advanced 

 w e x , ? ' Dut Medusa-disk; e, Polype-bud from side of Polype 

 before the detach- body, 

 ment of the top- 

 most disk this circle disappears, and a new one is developed at the 

 summit of the bulb which remains at the base of the pile (c, c). 

 it last the topmost and largest disk begins to exhibit a sort of 



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