104 



MORPHOLOGY. 



of the zooids of the trophosome may emit buds which will diverge from the direct Hne of succession, 

 and which may then either form the starting point for another similar line of succession, or may be 

 destitute of all power of continuing the succession of the zooids. Thus (woodcut, fig. 43) the 

 primordial hydranth, or any of its derivative hydranths, may repeat itself by a bud which will 

 diverge from the direct line, produce other zooids by gemmation, and thus start off a new series, 

 as expressed in the following formula : 



VI. h ] + 



h -{- h-{- h-\- 



&c. 4" 6ls -\- ffph 

 &c. -)- bis -\- ffph 



X h 



{} 



&c. 



And this state of things may also repeat itself indefinitely, giving rise to an indefinite number of 

 collateral series, diverging from one another and from the primary axis of succession. 



Pig. 43. 



Diagram of Laomedea. 



a, a, a, a. Hydranths belonging to the primary or direct line of succession ; a', a', a', a', hydranths 

 belonging to a secondary or diverging line of succession ; I, blastostyle of the primary line of succession, 

 bearing gonophores and surrounded by a gonangium; b', blastostyle, with gonophores and gonaugium 

 of the diverging line. 



As already said, how^ever, the diverging zooid may have no power of continuing the succes- 

 sion. Thus, the spiral hydranth oi Hydradinia is not intercalated in the direct succession of 

 zooids. It is a diverging zooid, like that which starts off the collateral series in Formula VI, 



