318 



Descriptive Zoology. 



But instead of being simple most of them are compound, 

 or, as it is more commonly expressed, they live in colonies. 

 We have seen that hydra multiplies by budding. Imagine 

 a hydra in which the budding continues indefinitely, the 

 new individuals remaining connected with the parent, and 



FIG. 182. A HYDROID. 



After Allman. From Kingsley's Zoology. 



you have the hydroid colony. The relation between these 

 members of the colony is more than a mere mechanical 

 connection, for the internal cavity is continuous through the 

 colony, so that whatever one individual takes as food may 

 serve to nourish any one or all the other members of the 

 community. 



