Fig. 68. — Life History of a Hydrozoon, Bougainvillia truticosa. A. The zoophyte 

 colony, natural size. B. A portion enlarged, showing PE , protective perisarc ; 

 C. The living connexion between the polyps ; NP. a nutritive polyp, MB. a medu- 

 soid bud, M. a medusoid about to be liberated. C. A free-swimming sexual 

 medusoid. (After Allman.) 



