Growth of Hydroid Colonies. 



37 



into a stomach, from which four tubes radiate to the 

 margin of the bell, where they are united by a circular 



FIG. 22. 



Physalia or Portuguese Man of Wai : a, 6, c, three stages of growth ; a', air- 

 sac or float ; ir polypites, T tentacles. 



canal, in the walls of which, or within the wall of the 

 stomach, the eggs are formed 



