18 GEORGE T. HARGITT 



the same time that gonads are present. Medusae are formed 

 from a single tentacle base in Hybocodon prolifer, Amphicodon 

 amphipleurus Haeckel and others; from the bases of all tentacles 

 in Sarsia codonophora (fig. 13) ; from radial canals of Probosci- 

 dactyla ornata (fig. 9); from the margin of the bell in Niobia 

 dendrotentaculata (fig. 11); and from the gonads of Eucheilota 

 paradoxica (fig. 12) and other forms. These are merely examples 

 of the variation in the method of budding as recorded for numer- 

 ous medusae. In many of these the budding occurs during the 

 immature period, and only after budding ceases do the gonads 

 form, but others show no such periodicity and may produce buds 

 and germ cells simultaneously. 



The production of the buds from the gonads has been critically 

 studied. Mayer ('10) describes this process for Eucheilota (fig. 

 12) as involving the activity of the tissues of the gonad and of 

 the tissues outside the gonad ; both ectoderm and entoderm of the 

 parent take part in the production of the bud by a process of cell 

 multiplication and evagination. In Phialidium mccradyi buds are 

 also produced from the gonads, but only indirectly, since a blasto- 

 style is first formed and from this the medusae arise by budding. 

 Sigerfoos ('93), in the formation of the blastostyle and medusae, 

 discovered no difference from ordinary cases of budding, the 

 ectoderm and entoderm evaginating to produce the new growth. 

 The germ cells in the gonad play no part in the process other 

 than to behave as all other cells of ectoderm and entoderm, which 

 suggests the probability of the germ cells being merely body cells 

 capable of acting with other body cells or undergoing a growth 

 in preparation for sexual reproduction. 



Budding in medusae is typically an evagination of the two 

 body layers, irrespective of the part of the animal which produces 

 the bud, but a few medusae are Jknown to form their buds only 

 from the ectoderm. Mayer describes such a case in Bougain- 

 villia niobe, the ectoderm of the stomach wall differentiating to 

 form all the tissues and organs of the bud. Mayer believes a 

 possibility exists of the origin of the bud entoderm from parent 

 entoderm; but could find no evidence of such a connection, nor 

 of any union of the enteric cavities of bud and parent at any stage 



