148 



SENESCENCE AND REJUVENESCENCE 



zooids or hydranths at the tips of the branches results. Fig. 50 

 shows a portion of such a Pennaria colony. In this species the new 



Figs. 50-52. — Pennaria tiarella: Fig. 50, part of a colony, including a large, 

 old hydranth, h, bearing a medusa bud, m, a younger hydranth, h', and a hydranth 

 bud, h"; Figs. 51, 52, developmental stages of hydranth. 



hydranth bud arises laterally a short distance below the terminal 

 hydranth of a stem or branch (Fig. 50, h"). It is an outgrowth 



